What is general biology. Biology is a subject that reveals the basic laws of life

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A. A. Kamensky, E. A. Kriksunov, V. V. Pasechnik
Biology. General biology. 10-11 grades

Introduction

You are beginning to study the school course "General Biology". This is the conventional name of a part of the school course in biology, the task of which is to study the general properties of living things, the laws of its existence and development. Reflecting wildlife and man as a part of it, biology is acquiring ever greater importance in scientific and technological progress, becoming a productive force. Biology creates new technology - biological, which should become the basis of a new industrial society. Biological knowledge should contribute to the formation of biological thinking and ecological culture in each member of society, without which further development human civilization is impossible.

§ 1. Short story development of biology

1. What does biology study?

2. What biological sciences do you know?

3. Which biological scientists do you know?

Biology as a Science.You know well that biology is the science of life. At present, it represents the totality of the sciences of living nature. Biology studies all the manifestations of life: the structure, functions, development and origin of living organisms, their relationship in natural communities with the habitat and with other living organisms.

Since the man began to realize his difference from the animal world, he began to study the world around him. At first his life depended on it. Primitive people needed to know which living organisms can be eaten, used as medicines, for making clothes and dwellings, and which ones are poisonous or dangerous.

With the development of civilization, a person was able to afford such a luxury as engaging in science for cognitive purposes.

Studies of the culture of ancient peoples have shown that they had extensive knowledge about plants, animals and were widely used in everyday life.

Modern biology is a complex science characterized by the interpenetration of ideas and methods of various biological disciplines, as well as other sciences, primarily physics, chemistry and mathematics.

The main directions of development of modern biology.At present, three directions in biology can be conventionally distinguished.

First is classical biology. It is represented by naturalist scientists who study the diversity of wildlife. They objectively observe and analyze everything that happens in living nature, study living organisms and classify them. It is wrong to think that all discoveries have already been made in classical biology. In the second half of the XX century. not only many new species have been described, but large taxa have also been discovered, up to kingdoms (Pogonophora) and even over kingdoms (Archaea, or Archaea). These discoveries forced scientists to take a fresh look at the entire history of the development of living nature. For true natural scientists, nature is a value in itself. Every corner of our planet is unique for them. That is why they are always among those who acutely feel the danger to the nature around us and actively advocate for its protection.

The second direction is evolutionary biology. In the XIX century. theory author natural selection Charles Darwin started out as an ordinary naturalist: he collected, observed, described, traveled, revealing the secrets of living nature. However, the main result of his work, which made him a famous scientist, was the theory that explains organic diversity.

At present, the study of the evolution of living organisms is actively continuing. Synthesis of genetics and evolutionary theory led to the creation of the so-called synthetic theory of evolution. But even now there are still many unresolved questions, the answers to which are sought by evolutionary scientists.

Created at the beginning of the XX century. our outstanding biologist Alexander Ivanovich Oparin the first scientific theory the origin of life was purely theoretical. At present, experimental studies of this problem are being actively carried out, and thanks to the use of advanced physicochemical methods, important discoveries have already been made and new interesting results can be expected.

Charles Darwin (1809-1882)

Alexander Ivanovich Oparin (1894-1980)

New discoveries made it possible to supplement the theory of anthropogenesis. But the transition from the animal world to man still remains one of the greatest mysteries of biology.

The third direction - physical and chemical biology, examining the structure of living objects using modern physical and chemical methods. This is a rapidly developing area of \u200b\u200bbiology, which is important both in theoretical and practical terms. It is safe to say that new discoveries await us in physical and chemical biology, which will allow us to solve many problems facing mankind.

Development of biology as a science. Modern biology is rooted in antiquity and is associated with the development of civilization in the Mediterranean countries. We know the names of many outstanding scientists who have contributed to the development of biology. Let's name just a few of them.

Hippocrates (460 - c. 370 BC) gave the first relatively detailed description of the structure of humans and animals, pointed to the role of the environment and heredity in the occurrence of diseases. He is considered the founder of medicine.

Aristotle (384–322 BC) divided the surrounding world into four kingdoms: the inanimate world of earth, water and air; the world of plants; the world of animals and the world of man. He described many animals, laid the foundation for taxonomy. The four biological treatises he wrote contained almost all the information about animals known by that time. The merits of Aristotle are so great that he is considered the founder of zoology.

Theophrastus (372–287 BC) studied plants. He described more than 500 plant species, provided information on the structure and reproduction of many of them, introduced many botanical terms. He is considered the founder of botany.

Guy Pliny the Elder (23–79) collected information about living organisms known by that time and wrote 37 volumes of the Natural History encyclopedia. Almost until the Middle Ages, this encyclopedia was the main source of knowledge about nature.

Claudius Galen in his scientific research he widely used mammalian dissections. He was the first to make a comparative anatomical description of man and monkey. He studied the central and peripheral nervous system. Historians of science consider him the last great biologist of antiquity.

In the Middle Ages, the dominant ideology was religion. Like other sciences, biology during this period had not yet emerged into an independent field and existed in the general mainstream of religious and philosophical views. And although the accumulation of knowledge about living organisms continued, biology as a science at that time can only be spoken of conditionally.

The Renaissance era is a transition from the culture of the Middle Ages to the culture of the new era. The radical socio-economic transformations of that time were accompanied by new discoveries in science.

The most famous scientist of this era Leonardo da Vinci (1452-1519) made a certain contribution to the development of biology.

He studied the flight of birds, described many plants, the ways of connecting bones in joints, the activity of the heart and visual function of the eye, the similarity of the bones of humans and animals.

In the second half of the 15th century. natural science knowledge begins to develop rapidly. This was facilitated by geographical discoveries, which made it possible to significantly expand information about animals and plants. The rapid accumulation of scientific knowledge about living organisms led to the division of biology into separate sciences.

In the XVI-XVII centuries. botany and zoology began to develop rapidly.

The invention of the microscope (early 17th century) made it possible to study the microscopic structure of plants and animals. Microscopically small living organisms - bacteria and protozoa - invisible to the naked eye were discovered.

He made a great contribution to the development of biology Karl Linnaeus, who proposed a classification system for animals and plants.

Karl Maksimovich Baer (1792–1876) in his works formulated the main provisions of the theory of homologous organs and the law of embryonic similarity, which laid the scientific foundations of embryology.

Claudius Galen (c. 130 - c. 200)

Karl Linnaeus (1707-1778)

In 1808, in the work "Philosophy of Zoology" Jean Baptiste Lamarck raised the question of the causes and mechanisms of evolutionary transformations and presented the first theory of evolution in time.

Cell theory played a huge role in the development of biology, which scientifically confirmed the unity of the living world and served as one of the prerequisites for the emergence of the theory of evolution Charles Darwin. The authors of the cell theory are considered a zoologist Theodora Schwann (1818-1882) and botany Matthias Jakob Schleiden (1804–1881).

On the basis of numerous observations, Charles Darwin published in 1859 his main work "On the Origin of Species by Natural Selection or Preservation of Favored Breeds in the Struggle for Life", in which he formulated the main provisions of the theory of evolution, proposed mechanisms of evolution and ways of evolutionary transformation of organisms.

In the XIX century. thanks to works Louis Pasteur (1822–1895), Robert Koch (1843–1910), Ilya Ilyich Mechnikov microbiology took shape as an independent science.

XX century began with the rediscovery of laws Gregor Mendel, which marked the beginning of the development of genetics as a science.

In the 40-50s of the XX century. in biology, ideas and methods of physics, chemistry, mathematics, cybernetics and other sciences began to be widely used, and microorganisms were used as objects of research. As a result, biophysics, biochemistry, molecular biology, radiation biology, bionics, etc. arose and began to develop rapidly as independent sciences. Research in space contributed to the birth and development of space biology.

Jean Baptiste Lamarck (1774-1829)

Ilya Ilyich Mechnikov (1845-1916)

In the XX century. the direction of applied research appeared - biotechnology. This direction will undoubtedly develop rapidly in the 21st century. You will learn more about this direction in the development of biology when you study the chapter "Fundamentals of Breeding and Biotechnology".

At present, biological knowledge is used in all spheres of human activity: in industry and agriculture, medicine and energy.

Environmental research is extremely important. We finally began to realize that the delicate balance that exists on our small planet is easy to destroy. Humanity was faced with a daunting task - the preservation of the biosphere in order to maintain the conditions for the existence and development of civilization. It is impossible to solve it without biological knowledge and special research. Thus, at present, biology has become a real productive force and a rational scientific basis for the relationship between man and nature.

Gregor Mendel (1822-1884)

Classical biology. Evolutionary biology. Physical and chemical biology.

1. What directions in the development of biology can you single out?

2. What great scientists of antiquity made a significant contribution to the development of biological knowledge?

3. Why in the Middle Ages it was possible to speak about biology as a science only conditionally?

4. Why is modern biology considered a complex science?

5. What is the role of biology in modern society?

Prepare a message on one of the following topics:

1. The role of biology in modern society.

2. The role of biology in space research.

3. The role of biological research in modern medicine.

4. The role of outstanding biologists - our compatriots in the development of world biology.

How much the views of scientists on the diversity of living things have changed can be demonstrated by the example of the division of living organisms into kingdoms.

Back in the 40s of the XX century, all living organisms were divided into two kingdoms: Plants and Animals. Bacteria and fungi were also included in the plant kingdom. Later, a more detailed study of organisms led to the allocation of four kingdoms: Prokaryotes (Bacteria), Fungi, Plants and Animals. This system is given in school biology.

In 1959, it was proposed to divide the world of living organisms into five kingdoms: Prokaryotes, Protists (Protozoa), Mushrooms, Plants and Animals.

This system is often cited in biological (especially translated) literature.

Other systems have been developed and continue to be developed, including 20 or more kingdoms. For example, it is proposed to distinguish three super-kingdoms: Prokaryotes, Archaea (Archaea) and Eukaryotes. Each kingdom includes several kingdoms.

§ 2. Research methods in biology

1. How is science different from religion and art?

2. What is the main goal of science?

3. What research methods used in biology do you know?

Science as a sphere of human activity. Science is one of the spheres of human activity, the purpose of which is the study and knowledge of the surrounding world. For scientific knowledge, it is necessary to select certain objects of research, problems and methods of their study. Each science has its own research methods. However, no matter what methods are used, the principle "Take nothing for granted" is always the most important for every scientist. the main task science - building a system of reliable knowledge based on facts and generalizations that can be confirmed or refuted. Scientific knowledge is constantly challenged and accepted only with sufficient evidence. Scientific fact (Greek factum - done) is only one that can be reproduced and confirmed.

Scientific method (Greek methodos - the way of research) is a set of techniques and operations used to build a system of scientific knowledge.

The entire history of the development of biology clearly indicates that it was determined by the development and application of new research methods. The main research methods used in biological sciences are descriptive, comparative, historical and experimental.

Descriptive method. It was widely used by scientists of antiquity, who collected factual material and described it. It is based on observation. Almost until the 18th century. biologists mainly dealt with the description of animals and plants, made attempts to primary systematize the accumulated material. But the descriptive method has not lost its significance today. For example, it is used when discovering new species or studying cells using modern methods research.

Comparative method. It made it possible to identify the similarities and differences between organisms and their parts and began to be used in the 17th century. The use of the comparative method made it possible to obtain the data necessary for the systematization of plants and animals. In the XIX century. it was used in the development of cell theory and substantiation of the theory of evolution, as well as in the restructuring of a number of biological sciences based on this theory. Nowadays, the comparative method is also widely used in various biological sciences. However, if only descriptive and comparative methods were used in biology, then it would remain within the framework of the ascertaining science.

Historical method. This method helps to comprehend the obtained facts, to compare them with previously known results. It became widely used in the second half of the 19th century. thanks to the works of Charles Darwin, who with his help scientifically substantiated the regularities of the appearance and development of organisms, the formation of their structures and functions in time and space. The use of the historical method has made it possible to transform biology from a descriptive science into a science explaining how diverse living systems originated and how they function.

Experimental method. The use of the experimental method in biology is associated with the name William Harvey, who used it in his studies in the study of blood circulation. But it began to be widely used in biology only from the beginning of the 19th century, primarily in the study physiological processes... The experimental method allows you to study a particular phenomenon of life with the help of experience.

G. Mendel made a great contribution to the approval of the experimental method in biology, who, while studying heredity and variability of organisms, for the first time used the experiment not only to obtain data on the phenomena under study, but also to test the hypothesis formulated on the basis of the results obtained. The work of G. Mendel has become a classic example of the methodology of experimental science.

William Harvey (1578-1657)

In the XX century. the experimental method became the leading one in biology. This became possible due to the emergence of new devices for biological research (electron microscope, tomograph, etc.) and the use of methods of physics and chemistry in biology.

At present, various types of microscopy are widely used in biological experiments, including electronic microscopy with the technique of ultrathin sections, biochemical methods, various methods of cultivation and intravital observation of cell, tissue and organ cultures, the method of labeled atoms, X-ray diffraction analysis, ultracentrifugation, chromatography, etc. It is no coincidence that in the second half of the XX century. in biology, a whole direction has developed - the creation of the latest instruments and the development of research methods.

Biological research is increasingly using modeling, which is considered the highest form of experiment. So, are active work on computer modeling of the most important biological processes, the main directions of evolution, the development of ecosystems or even the entire biosphere (for example, in the case of global climatic or technogenic changes).

The experimental method, combined with the systemic-structural approach, radically transformed biology, expanded its cognitive capabilities and opened new ways for using biological knowledge in all spheres of human activity.

Scientific fact. Scientific method. Research methods: descriptive, comparative, historical, experimental.

1. What is the main goal and task of science?

2. Why can it be argued that the development of biology was determined by the development and application of new scientific research methods?

3. How important were descriptive and comparative methods for the development of biology?

4. What is the essence of the historical method?

5. Why is the experimental method most widespread in the 20th century?

Suggest research methods that you will apply when studying anthropogenic impact on an ecosystem (water body, forest, park, etc.).

Suggest some of your options for the development of biology in the 21st century.

What diseases, in your opinion, will be defeated by humanity using the methods of molecular biology, immunology, genetics in the first place.

Scientific research, as a rule, consists of several stages (Fig. 1). Based on the collection of facts, the problem is formulated. To solve it, hypotheses (Greek hypothesis - an assumption). Each hypothesis is tested experimentally in the course of obtaining new facts. If the facts obtained contradict the hypothesis, then it is rejected. If the hypothesis is consistent with the facts and allows correct predictions to be made, then it can become theory (Greek theoria - research). However, even a correct theory can be revised and refined as new facts accumulate. The theory of evolution is a good example.

Some theories are about establishing links between different phenomena. it regulations and the laws.

There are exceptions to the rules, but laws always apply. For example, the law of conservation of energy is valid for both living and nonliving nature.

Figure: 1. The main stages of scientific research

§ 3. The essence of life and properties of living

1. What is life?

2. What is considered the structural and functional unit of the living?

3. What properties of living things do you know?

The essence of life. You already know that biology is the science of life. But what is life?

The classical definition of the German philosopher Friedrich Engels: "Life is a way of existence of protein bodies, the essential point of which is a constant metabolism with the surrounding external nature, and with the termination of this metabolism, life also stops, which leads to the decomposition of protein" - reflects the level of biological knowledge of the second half of XIX in.

In the XX century. numerous attempts have been made to define life, reflecting the many-sided nature of this process.

All definitions contained the following postulates that reflect the essence of life:

- life is a special form of motion of matter;

- life is the metabolism and energy in the body;

- life is vital activity in the body;

- life is self-reproduction of organisms, which is ensured by the transfer of genetic information from generation to generation.

Life is a form of movement of matter higher than the physical and chemical forms of its existence.

In the most general sense a life can be defined as active maintenance and self-reproduction of specific structures consisting of biopolymers - proteins and nucleic acids, coming with the expenditure of energy received from the outside.

Neither nucleic acidsnor proteins in isolation are the substrate of life. They become a substrate of life only when they are found and function in cells. Outside of cells, these are chemical compounds.

According to the Russian biologist VM Volkenshtein, "living bodies that exist on Earth are open self-regulating and self-reproducing systems built from biopolymers - proteins and nucleic acids."

Properties of the living. A number of common properties are characteristic of living things. Let's list them.

1. Unity of chemical composition. Living things are formed by the same chemical elements as inanimate objects, but in living things 90% of the mass falls on four elements: C, O, N, H, which are involved in the formation of complex organic molecules, such as proteins, nucleic acids, carbohydrates , lipids.

2. The unity of the structural organization. The cell is a single structural and functional unit, as well as a unit of development for almost all living organisms on Earth. Viruses are an exception, but their properties of a living manifest themselves only when they are in a cell. There is no life outside the cell.

3. Openness. All living organisms are open systems, that is, systems that are stable only under the condition of a continuous supply of energy and matter from the environment.

4. Metabolism and energy. All living organisms are capable of metabolism with the environment. Metabolism is carried out as a result of two interrelated processes: the synthesis of organic substances in the body (due to external energy sources - light and food) and the process of decomposition of complex organic substances with the release of energy, which is then consumed by the body.

Metabolism ensures the constancy of the chemical composition in continuously changing environmental conditions.

5. Self-reproduction(reproduction). The ability to reproduce itself is the most important property of all living organisms. It is based on information about the structure and functions of any living organism, embedded in nucleic acids and providing the specificity of the structure and vital activity of a living organism.

6. Self-regulation. Any living organism is exposed to continuously changing environmental conditions. At the same time, certain conditions are necessary for the course of vital processes in cells. Thanks to the mechanisms of self-regulation, the relative constancy of the internal environment of the body is maintained, that is, the constancy of the chemical composition and the intensity of the course of physiological processes are maintained (in other words, homeostasis is maintained: from the Greek homoios - the same and stasis - the state).

7. Development and growth. In the process of individual development (ontogenesis), the individual properties of the organism are gradually and consistently manifested and its growth is carried out. In addition, all living systems evolve - change in the course of historical development (phylogenesis).

8. Irritability. Any living organism is capable of selectively reacting to external and internal influences.

9. Heredity and variability. The continuity of generations is ensured by heredity. Descendants are not copies of their parents due to the ability of hereditary information to change - variability.

Some of the properties listed above may be inherent in inanimate nature. For example, crystals in a saturated salt solution can "grow". However, this growth does not have those qualitative and quantitative parameters that are inherent in the growth of living things.

A burning candle is also characterized by metabolic processes and energy conversion, but it is not capable of self-regulation and self-reproduction.

Therefore, all of the above properties in their totality are characteristic only for living organisms.

A life. Open system.

1. Why is it very difficult to define the concept of "life"?

2. What is the difference chemical organization living organisms from objects of inanimate nature?

3. Why are living organisms called open systems?

4. What is the fundamental difference between metabolic processes in living organisms and in inanimate nature?

5. What is the role of variability and heredity in the development of life on our planet?

Compare the essence of the processes of growth, reproduction and metabolism in inanimate nature and in living organisms.

Give examples of properties characteristic of a living organism that can be observed in inanimate objects.

Organism (Lat. organizo - I arrange) is an individual, an individual (Lat. individuus - indivisible), independently interacting with its environment. The term "organism" is easy to understand, but almost impossible to define unequivocally. An organism can consist of one cell and can be multicellular. Different colonial organisms can consist of homogeneous organisms, for example, Volvox, or be a complex of highly differentiated individuals that make up a single whole, for example, the Portuguese boat is a colonial coelenterate animal. Sometimes even individuals separated from each other form groups that differ in certain individual properties: for example, in bees, like in other social insects, a family has a number of properties of an organism.

One of the most ancient, but at the same time progressive sciences even today is biology. This is a science that studies all the diversity of living nature around us. After all, every day we are faced with hundreds of living things: insects, bacteria, viruses, plants and, of course, people. Each organism has its own characteristics of structure and life, all are interconnected by certain laws and are in various kinds of relationships. All this is studied by such an extensive, fascinating and truly great science as biology.

Biosphere of planet Earth

Our planet is inhabited by a wide variety of life forms. All of them, interacting with each other, form a common shell. The living shell of the planet Earth. It is called the biosphere. In addition to the biosphere, our planet has shells such as the hydrosphere, lithosphere and atmosphere. Naturally, the entire biomass of the biosphere envelope could not exist separately from other envelopes. Therefore, this division is very arbitrary. In fact, each of the shells contains representatives of the biosphere.

For example, the lithosphere is densely populated with worms, bacteria, larvae, insects and mammals. It is also in it that the lower parts of most existing land plants are located.

The hydrosphere, represented by the totality of all types of water on Earth, is generally a whole world, beautiful and interesting, in terms of its biomass composition. The atmosphere is no exception. Various bacteria, viruses, insects, birds and even mammals are an integral part of it and use it for permanent residence. Moreover, in general, almost all living things (with the exception of some types of bacteria) are able to live only in aerobic conditions, that is, in the conditions of the earth's atmosphere.

The entire biomass of the biosphere envelope is a multi-million community of living beings. And such a science of living nature as biology, with all the departments included in it, is precisely engaged in the most detailed study of this great community.

Methods and materials used in biology

For a comprehensive analysis and a convenient and detailed examination of all living objects of nature in biology, special materials are used. Such as:

• scalpel;
• clamps;
• forceps;
• measuring instruments;
• stain traps;
• mortars and pestles;
• test tubes;
• trays and Petri dishes;
• dissecting needles and tables;
• mirrors and magnifiers;
• very different and so on.

This, of course, is not a complete list of the whole variety of materials that help biologists in the knowledge of living things and in scientific research.

There are also specific techniques that biology uses as a science. Biology methods are diverse, but the main ones include the following.

Biological methodology

Scientific methods of biology

Method name	Materials used	Practical value
Observation	Field diary, binoculars, magnifying glass, microscope, video and photo equipment, etc.	Obtaining visual information about the observed object without interfering with natural processes, the accumulation of useful information.
Description	Computer, stationery, paper.	Fixation of those results that were obtained by the observation method. This method provides historical significance for the preservation of useful information.
Experiment	Laboratory equipment, microscope, etc.	Practical confirmation of the scientific hypotheses put forward.
Comparison	Literature or experiments on the topic.	It makes it possible to choose a more correct result, and also shows all the differences in life, the structure of organisms, depending on various factors.
Modeling (includes generalization, systematization)	Materials for creating models of the studied object.	Allows you to recreate a picture of ongoing processes and predict the result.
Analytical method	Measuring devices, computers	Allows you to derive general patterns or differences in living nature, and also provides a systematization of the accumulated knowledge.
Modern methods: X-ray structural analysis (X-ray structural analysis); centrifugation; radiography; cytochemistry (histochemistry); cultivation of organisms on nutrient media; microscopy (electronic, fluorescent, contrast, dark-field); lifetime staining.	Centrifuges, special microscopes, Petri dishes, agar-based, specific equipment and instruments.	Provide accurate analysis of the smallest living units, give full information about the processes occurring at the molecular level. They allow you to interfere with the genome and set the desired properties for living organisms.

As a result, we get the following result. Biology is a science that studies living systems completely, comprehensively and using a wide variety of modern technologies.

The main sections of biology

Today biology has dozens of secondary young sciences that arose from it due to the accumulation of a large amount of various knowledge in the most delicate issues related to living systems. We will highlight the main, historically formed sections of biological science.

1. General biology.
2. Genetics.
3. Zoology.
4. Botany.
5. Physiology of plants and animals.
6. Anatomy.
7. Human physiology.
8. Ecology.
9. Biogeography.
10. Biochemistry.

First of all, biology is the science of nature. Therefore, all of the listed sections are fundamental in the context of considering this science.

General biology: essence, subject of study

This name means the study of the main life moments of each living system: the emergence, development, formation in nature, functioning. Consequently general biology includes the following sections:

• Cell theory and cell structure.
• Ontogenesis of organisms.
• Molecular biology.
• Genetics.
• Evolution of all living things.
• Ecology.
• The doctrine of the biospheric envelope of the Earth.

From the above list, it becomes clear that this biology is a science that studies the universal characteristics inherent in all living systems as a whole. In the school course, general biology is taught in high school, from 9 to 11 inclusive. And this is correct, because the concepts that it includes are quite complex, voluminous and require an already more formed worldview of students.

Botany in the school course

Today, scientists have cited a figure of approximately 350,000 species when it comes to the diversity of modern plants. Naturally, this figure is too large, and plants are unique and interesting, so that a separate science does not form, which is exclusively concerned with their study. Botany, a branch of biology, belongs to such a science.

All plants can be divided into terrestrial and aquatic. But this is only very rough, surface classification... In fact, there are many taxa, genera, species, subspecies and other taxonomic units into which plants are subdivided. This is the essence of one of the departments of botany.

There are also a number of other departments covering all aspects of plant life:

• plant morphology;
• plant physiology;
• ecology;
• biogeography;
• phylogeny;
• evolution;
• economic botany.

The totality of all these sciences, as well as those departments that are included in each of them, in turn, allows for a comprehensive total study of any plant organism. Therefore, we can say with confidence that biology is the science of plants.

Botany is studied in the school biology course in grades 6-7, depending on the curriculum. Phylogeny and evolution are studied in grade 11.

Zoology in the school course

Over 1,350,000 species of representatives of the animal world have been described by zoology. The overwhelming majority are invertebrates - insects, worms, marine life. This figure is not final, because zoologists do not stop their research. Despite the fact that, it would seem, there is nothing to discover and all the animals are known, new species are discovered periodically.

Zoology is one of the oldest sciences that includes biology. Animals are one of the most widespread and ubiquitous living systems on our planet. Zoology deals with the study of the structure (both external and internal) of all animals, their taxonomy, physiology, anatomy, ethology, ecology and geography.

Just like botany, zoology is an obligatory section of biological science to study at school. Her course falls on grade 7.

The role of biology in human life

Biology is a science that studies and covers so many different spheres of life that there is no doubt about its importance and significance. The main examples that will clearly show and prove this are the following:

1. Animals that are immune to cancer (sharks and rays) are an excellent basis for finding and discovering a cure for this 21st century disease.
2. Achievements of microbiologists, biochemists and medical biologists allow mankind to get rid of many different ailments, including those of viral and bacterial nature.
3. Biotechnology, cellular and provides the opportunity to increase productivity agriculture and provide food for entire nations.
4. Anthropological biology allows you to identify the origins of all living things, recreate the picture of the world and avoid mistakes in the future.

These are not all the reasons and circumstances that make it possible to speak of biology as an extremely important and significant science in the life and practice of people.

New sections of biology

The modern, young and promising areas of biological science include:

• biotechnology;
• microbiology;
• cell engineering;
• genetic Engineering;
• molecular biology;
• biochemistry;
• medical biology.

The whole complex of these sciences makes it possible to characterize any creature belonging to a living system. Therefore, biology is the science of living nature, first of all, and of the benefits that it can give to humans.

Biology at school

Biology is indirectly affected already at the stage of the course in natural history (grade 5 of the school curriculum). Precisely as a subject, it begins from grade 6 (botany), grade 7 - zoology, grade 8 - anatomy, 9-11 - general biology.

The school course of this science touches on a variety of topics in biology, which relate to almost all of its branches and sections. This is done to form a holistic picture of the perception of the world in children, as well as for students to clearly assimilate the importance and significance of the achievements of biological sciences in the modern world.

General biology

It should be noted that in the opinion of scientists, in modern science, the results of which are usually published in journals with a high impact factor, there is no such science as General Biology, similar to General Physics. However, leading universities teach courses for first-year bachelors, that is, "General Biology" exists only as an introductory course in biology.

History

In 1802, the term biology appears. G.R. Treviranus defines biology as the science of general characteristics in animals and plants, as well as special subject headings that were studied by his predecessors, in particular K. Linnaeus.

In 1832, the book "Allgemeine Biologie der Pflanzen" ("General Biology of Plants") (Geifsv., 1832) was published, which is a translation of the book "Lärobok i botanik" by Karl Agar.

Already in 1883, courses in general biology were taught at the University of New Zealand.

General biology as a separate course began to be taught in the first half of the 20th century, which was associated with successes in the study of cells, microbiological research, discoveries of genetics, in a word, the transformation of biology from an auxiliary, private, descriptive science (zoology, botany, taxonomy) into an independent and extremely demanded area of \u200b\u200bknowledge.

In 1940, Academician II Shmalgauzen founded the "Journal of General Biology".

Apparently the first book (textbook) on general biology in Russian was V.V. Makhovko, P.V. Makarov, K. Yu. Kostryukova General Biology Publishing House: State Publishing House of Medical Literature, 1950 504 pp.

How general biology is taught in high school high school since 1963, and in 1966 the book "General Biology" edited by Yu.I. Polyansky was published, used as a textbook.

Main sections

Traditionally, general biology includes: cytology, genetics, biological chemistry, molecular biology, biotechnology [ not in source], ecology, developmental biology, evolutionary doctrine, the doctrine of the biosphere and the doctrine of man (biological aspect) [not in source] .

The importance of general biology

Related sciences

Theoretical biology

see also

• Private biology

Notes

Literature

• Jane M. Oppenheimer, Reflections on Fifty Years of Publications on the History of General Biology and Special Embryology, Vol. 50, No. 4 (Dec., 1975), pp. 373-387
• Grodnitsky D.L., Comparative analysis of school textbooks on General Biology, 2003
• Fundamentals of General Biology (Kompendium Der Allgemeinen Biologie, GDR) Under the general editorship of E. Libbert M .: Mir, 1982.436 pp.

Links

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See what "General Biology" is in other dictionaries:

BIOLOGY - BIOLOGY. Contents: I. History of Biology .............. 424 Vitalism and Machinism. The emergence of empirical sciences in the XVI XVIII centuries. The emergence and development of evolutionary theory. The development of physiology in the XIX century. Development of cellular learning. Results of the XIX century ... Great medical encyclopedia

- (Greek, from bios life, and logos word). The science of life and its manifestations in animals and plants. Dictionary of foreign words included in the Russian language. Chudinov AN, 1910. BIOLOGY, Greek, from bios, life, and logos, word. The doctrine of life force. ... ... Dictionary of foreign words of the Russian language

BIOLOGY - uch. a subject at school; basics of knowledge about wildlife. Reflects modern. achievements of sciences studying the structure and life of biol. objects of all levels of complexity (cell, organism, population, biocenosis, biosphere). Shk. B. course includes sections: ... ... Russian Pedagogical Encyclopedia

- (from Bio ... and ... Logia is the totality of sciences about living nature. The subject of study is B. all manifestations of life: the structure and functions of living beings and their natural communities, their distribution, origin and development, connections with each other and with inanimate ... ... Big soviet encyclopedia

- (systems theory) a scientific and methodological concept for the study of objects that are systems. It is closely related to the systems approach and is the concretization of its principles and methods. The first version of general systems theory was ... ... Wikipedia

I Biology (Greek bios life + logos doctrine) is a set of natural sciences about life as a special phenomenon of nature. The subject of study is the structure, functioning, individual and historical (evolution) development of organisms, their relationship ... Medical encyclopedia

BIOLOGY - (from Greek, bios life and logos doctrine), a set of sciences about living nature. The subject of study is all manifestations of life: the structure and functions of living organisms, their distribution, origin, development, connections with each other and with inanimate nature. The term ... ... Veterinary encyclopedic dictionary

Biology - subject at school; the basics of knowledge about wildlife. Reflects the modern achievements of sciences studying the structure and vital activity of biological objects of all levels of complexity (cell, organism, population, biocenosis, biosphere). School ... ... Pedagogical terminological dictionary

General biology - - a part of biology that studies and explains the general, true for the whole variety of organisms on Earth ... Glossary of terms on the physiology of farm animals

This term has other meanings, see Variance. Variance is a term for the diversity of traits in a population. One of the quantitative characteristics of the population. To describe asexual and hermaphrodite populations, except for variances according to ... ... Wikipedia

Books

• General biology, V. M. Konstantinov, A. G. Rezanov, E. O. Fadeeva, The textbook is devoted to general issues of modern biology. It provides basic information about the structure of living matter and the general laws of its functioning. The topics of the training course are outlined: ... Category:

Biology– the science of living nature, which studies life as a special form of matter, the laws of its existence and development. Biology, first of all, is a complex of knowledge about life and a set of scientific disciplines (more than 300) that study living things: chemical composition, fine and coarse structure, distribution, functioning, its past, present and future, as well as its practical significance and application. The term "biology" in the modern sense was introduced simultaneously in 1802 by J.-B. Lamarck and the German natural scientist G.R. Treviranus.

Subject biology research - all manifestations of life:

Structure and function, development and distribution of living organisms (prokaryotes, protists, plants, fungi, animals and humans);

The structure, functions and development of natural communities, their relationship with each other and the environment;

Historical development and evolution of living organisms.

Taskswhich biology solves:

Identification and explanation of the general properties and diversity of living organisms;

Cognition of patterns in the structure and functioning of living systems of different ranks, their interconnections, stability and dynamism;

Study of the historical development of the organic world;

Drawing up a scientific picture of the world based on the data obtained;

Ensuring the safety of the biosphere and the ability of nature to reproduce itself.

Methodsused to solve problems:

- observation: makes it possible to describe biological phenomena;

- comparison: allows you to find patterns common to various phenomena;

- experimental (experience): the researcher artificially creates a situation that helps to study the properties of biological objects;

- modeling: with the help of computer technology, individual biological processes or phenomena are simulated (behavior of a biological system in given parameters):

- historical: allows, based on data on the modern organic world and its past, to study the processes of development of living nature (first used by Charles Darwin).

To describe and study biological processes, biologists also use methods: chemical, physical, mathematical, technical sciences, geography, geology, geochemistry, etc. As a result, related (borderline) disciplines arise - biochemistry, biophysics, soil science, radiobiology, radioecology, etc. .d.

All sciences can be classified:

· on the subject of study:

- zoology (studies the origin, structure and development of animals, their way of life, distribution on the globe), including more narrow disciplines - entomology (about insects) ornithology(about birds) ichthyology(about fish), theriology (about mammals);

- botany(studies propagating organisms, their origin, structure, development, vital activity, properties, diversity, classification, as well as the structure, development and location of plant communities on the earth's surface - phytocenoses), within which bryology (about mosses), dendrology (about trees) are distinguished;

- microbiology (microorganisms);

- mycology (mushrooms);

- lichenology (lichens);

- algology(seaweed);

- virology (viruses);

- hydrobiology (studies organisms living in the aquatic environment), etc .;

· on the study of the properties of the organism:

- anatomyand morphology (the subject of their study is the external and internal structure and form of organisms);

- physiology (studies the functions of living organisms, their interconnection, dependence on external and internal conditions); subdivided into human physiology, physiology of animals, plants, etc .;

- cytology (studies the cell as a structural and functional unit of organisms;

- histology (studies the structure of tissues of animal organisms);

- embryology and biology of individual development (studies the patterns of individual development);

- ecology (studies the way of life of animals and plants in their relationship with environmental conditions), etc.

· on the use of certain research methods:

- biochemistry (studies the chemical composition of organisms, the structure and function of chemicals by chemical methods);

- biophysics (studies physical and physicochemical phenomena in cells and organisms using physical methods);

- biometrics(based on the measurement of living bodies, their parts, processes and reactions and the subsequent calculation, carries out mathematical processing of data in order to establish dependencies, patterns that are invisible in the description of individual phenomena and processes), etc.;

- genetics (studies the laws of heredity and variability);

· on the practical application of biological knowledge:

- biotechnology (a set of industrial methods that make it possible to use living organisms with high efficiency to obtain valuable products - antibiotics, amino acids, proteins, vitamins, hormones, etc., to protect plants from pests and diseases, to deal with environmental pollution, in sewage treatment plants, etc. .d.);

- agrobiology (a set of knowledge about the cultivation of agricultural crops);

- selection (the science of methods of creating varieties of plants, animal breeds and strains of microorganisms with the properties necessary for humans);

- animal husbandry, veterinary medicine, medical biology, phytopathology and etc.;

· to study the level of organization of the living:

- molecular biology(examines life phenomena at the molecular genetic level and takes into account the significance of the three-dimensional structure of molecules);

- cytologyand histology (study cells and tissues of living organisms);

- population-species biology(studies populations);

- biocenology (studies biogeocenoses);

- general biology (studies general laws that reveal the essence of life);

- biogeography (studies the general laws of the geographical distribution of living organisms on Earth;

- taxonomy(studies the diversity of organisms and their distribution into groups);

- paleontology (studies the history of the organic world by the remains of animals and plants);

- evolutionary teaching(studies the historical development of living nature and the diversity of the organic world).

Practical significance and application of the achievements of modern biology:

1. Biology is the theoretical basis of many sciences.

2. Knowledge of biology is necessary for understanding the place of man in the system of nature, understanding the interrelationships of organisms and the inanimate nature surrounding them.

3. Biology has a decisive influence on the progress of agricultural production and medicine:

Environmental protection;

Recognition, prevention and treatment of diseases of plants, animals and humans;

Expansion of the scale of fish farming and fur farming;

Involvement of new territories in the economic turnover;

Development of selection of microorganisms, plants and animals;

Forecasting ecological situations in different regions and the state of the biosphere in general.

4. Biological training occupies a special place in the medical education system.

5. Many biological principles and provisions

Used in technique:

They are the basis of a number of industries in the food, light, microbiological, and other industries.

6. Modern biotechnologies based on cellular and genetic engineering (obtaining strains of microorganisms capable of synthesizing human insulin, somatotropic hormone, interferons, immunogenic drugs, vaccines, etc.) are widely introduced.

8. Genetic research has made it possible to develop methods for early (prenatal) diagnosis, treatment and prevention of many hereditary human diseases.

Self-renewal – the ability of organisms to constantly renew structural elements - molecules, enzymes, organelles, cells - by replacing the "worn out" ones that have fulfilled their functions (blood cells, skin epidermal cells, etc.).In this case, organisms use substances and energy that enter the cells ( flow of matter and energy). Self-renewal provide metabolism and energy conversion, matrix synthesis reactions, discreteness.

Self-reproduction – the ability of living organisms to produce their own kind while preserving the structure and functions of parental forms in the descendants... When living organisms reproduce, the offspring are usually similar to their parents: cats give birth to kittens, dogs - puppies. A dandelion will grow again from dandelion seeds. Reproduction also provides the property of self-reproduction. The self-replication process is carried out at almost all levels of the organization. Thanks to reproduction, not only whole organisms, but also cells, cell organelles (mitochondria, plastids) after division are similar to their predecessors. From one DNA molecule, when it is duplicated, two daughter molecules are formed, completely repeating the original one. Self-reproduction is based on matrix synthesis reactions, i.e., the formation of new molecules and structures based on information ( information flow) embedded in the DNA nucleotide sequence. Consequently, self-reproduction is closely related to the phenomenon heredity.

Self-regulation – the ability of organisms in continuously changing environmental conditions to maintain the constancy of their chemical composition and the intensity of physiological processes (homeostasis) based on the flow of matter, energy and information. At the same time, the lack of income nutrients mobilizes the internal resources of the body, and the excess causes the storage of these substances. Self-regulation is carried out in different ways due to the activity of regulatory systems - nervous and endocrine - and is based on principle feedbacks : a signal to turn on a particular system can be a change in the concentration of a substance or the state of a system. Thus, an increase in the concentration of glucose in the blood leads to an increase in the production of the pancreatic hormone insulin, which reduces the content of this sugar in the blood; lowering blood glucose levels slows down the release of the hormone into the bloodstream. A decrease in the number of cells in the tissue (during peeling, dermabrasion of the skin, as a result of injury) causes an increased proliferation of the remaining cells; restoration of the normal number of cells signals the cessation of intensive cell division).

Of the other properties characteristic of living things, some are in one way or another similar to the processes taking place in inanimate nature.

Unity of chemical composition. Living organisms are quite clearly demarcated from non-living organisms by their chemical composition (nucleic acids, proteins, carbohydrates, fats, etc.). Living things are composed of the same elements as objects of inanimate nature. But they form complex molecules in the body that are not found in inanimate nature. In addition, the ratios of these elements in the living and inanimate are also different. If the elementary composition of inanimate nature, along with oxygen, is silicon, iron, magnesium, aluminumand so on, then in living organisms 98% of the chemical composition is accounted for only by four elements - carbon, nitrogen, hydrogen and oxygen. In addition, all living organisms are built mainly from four groups of complex organic molecules: proteins, carbohydrates, lipids, and nucleic acids. It should be noted that the composition chemical elements in different environments inanimate nature, in contrast to living organisms, is different. The hydrosphere is dominated by hydrogen and oxygen, in the atmosphere - nitrogen and oxygen, in the lithosphere - silicon and oxygen.

Metabolism and energy conversion... it the common property of all living things is the totality of all chemical transformations occurring in the body and ensuring the preservation and reproduction of life. Organism- an open system in a stable stationary state:the rate of continuous flow of substances and energy from the environment is balanced by the rate of continuous transfer of substances and energy from the system.

The body consumes substances and energy from the environment, uses them to provide chemical reactions, and then returns to the environment, but in a different form, an equivalent amount of energy (in the form of heat) and matter (in the form of decay products). Organisms consume substances from the environment in the process nutrition. Autotrophs - plants, most protists and some part of prokaryotes, capable of photosynthesis, themselves create organic substances from inorganic ones with the help of light energy. Heterotrophs - animals, fungi, some protists and most prokaryotes use organic substances of other organisms, break them down with enzymes and assimilate the products of breakdown.

A significant part of organic substances (carbohydrates, proteins, lipids), supplied as a result of autotrophic or heterotrophic nutrition, contain in chemical bonds energy. During breathing, this energy is released and accumulated in ATP. Metabolic end products, often toxic, in the process discharge, or excretion excreted from the body.

Thus, organisms are characterized by metabolism with the environment and energy dependence. Metabolism and energy conversion ensure the constancy of the chemical composition and structure of all parts of the body and, as a result, the constancy of their functioning in continuously changing environmental conditions. Other signs - growth, irritability, heredity, variability, reproduction - all this is the result of metabolism and its manifestation.

Reproduction... When organisms reproduce, they produce their own kind and thereby increase the number of individuals. In the process of reproduction, characteristics, properties and developmental characteristics of organisms of a given species are transmitted from generation to generation. Thanks to reproduction, the number of the species is maintained for a long time at a certain level. The change of generations is ensured by sexual and asexual reproduction.

Heredity. Consists in the ability of organisms during reproduction to transmit their characteristics, properties and developmental characteristics from generation to generation... Heredity is based on the stability of carriers of genetic information, i.e., the constancy of the structure of DNA molecules. The genetic information contained in DNA determines the possible development limits of an organism, its structures, functions and reactions to the environment. At the same time, offspring are usually similar to their parents, but not identical to them.

Variability. The ability of organisms to acquire new properties and characteristics during ontogenesis and lose old ones,called variability. This property is, as it were, the opposite of heredity, but at the same time is closely related to it, since this changes the genes that determine the development of certain characteristics. If the reproduction of matrices - DNA molecules - always took place with absolute accuracy, then during the reproduction of organisms, only the succession of previously existing characters would be carried out, and the adaptation of species to changing environmental conditions would be impossible. Hence, variability Is the ability of organisms to acquire new traits and properties, which is based on changes in DNA molecules. Thus, self-doubling of DNA molecules makes it possible not only to preserve the hereditary characteristics of the parents in the offspring, but also to deviate from them, that is, variability, as a result of which organisms acquire new traits and properties. Variability creates a variety of material for natural selection, i.e., the selection of the most adapted individuals to the specific conditions of existence in natural conditions, which, in turn, leads to the emergence of new forms of life, new types of organisms.

Growth and development. Regardless of the method of reproduction (asexual or sexual), all daughter individuals formed from one zygote, spore, kidney or cell are inherited only genetic information, that is, the ability to display certain signs and properties. The new organism implements the received hereditary information during growth and development. Development – change in the external or internal structure of the body.The development of living organisms is presented ontogenesis (individual development) and phylogenesis (historical development)... During ontogenesis, the individual properties of the organism gradually and consistently manifest themselves (the manifestation of eye color, the ability to hold the head, sit, walk, the appearance of teeth, etc. in children). Development is accompanied by growth – a gradual increase in the size of a developing organism,due to the process of increasing the number of cells and the accumulation of a mass of extracellular formations as a result of metabolism. In the process of development, a specific structural organization individual, and an increase in its mass is due to the reproduction of macromolecules, elementary structures of cells and the cells themselves. With the change of numerous generations, a change in species occurs, or phylogenesis (evolution) – it is the irreversible and directed development of living nature, accompanied by the formation of new species and the progressive complication of life.

Irritability. In the process of evolution, organisms have developed property to selectively react to the effects of the external or internal environment– irritability. For example, in mammals, when the body temperature rises, the blood vessels of the skin dilate, dissipating excess heat and thereby restoring the optimal body temperature.

Any change in environmental conditions surrounding the body isirritant , and the body's reaction to external stimuli serves as an indicator of its sensitivity and a manifestation of irritability. The most striking form of irritability is motion... In plants it is tropisms and nastia, for protist - taxis; reactions of multicellular organisms - reflexesimplemented through nervous system... The combination "stimulus - reaction" can be accumulated in the form of experience and used by the body in the future.

Adaptation to the environment. Living organisms are not only well adapted to their environment, but also perfectly fit their way of life. Features of the structure, life and behavior that ensure survival and reproduction in their habitat are called adaptations (devices).

Discreteness and integrity... Discreteness is a universal property of matter: each atom consists of elementary particles, atoms form a molecule. Simple molecules are part of complex compounds or crystals, etc. Living systems differ sharply from inanimate objects in their exceptional complexity and high structural and functional ordering. At the same time, a separate organism, or another biological system (species, biogeocenosis, etc.), is discrete and integral, that is, it consists of separate isolated (isolated and delimited in space), but nevertheless closely related and interacting between are parts that form a functional unity. Any kind of organism includes individual individuals. The body of a highly organized individual forms spatially delimited organs, which, in turn, consist of individual cells. The energy apparatus of the cell is represented by mitochondria, the apparatus of protein synthesis is represented by ribosomes, etc. up to macromolecules (proteins, nucleic acids, etc.), each of which can perform its function only being spatially isolated from the others. Discreteness of the structure of an organism is the basis of its structural order, it creates the possibility of its constant self-renewal by replacing "worn out" structural elements without termination of the performed function. The discreteness of a species determines the possibility of its evolution by the death or elimination of unadapted individuals from reproduction and the preservation of individuals with traits useful for survival.

A guide for applicants to universities
Author Galkin.

Introduction.

Biology is the science of life. This is a collection of scientific disciplines that study living things. Thus, the object of research in biology is life in all its manifestations. What is life? There is still no complete answer to this question. Of the many definitions of this concept, we present the most popular. Life is a special form of existence and the physicochemical state of protein bodies, characterized by a mirror asymmetry of amino acids and sugars, metabolism, homeostasis, irritability, self-reproduction, systemic self-government, adaptability to the environment, self-development, movement in space, information transfer, physical and functional discreteness of individual individuals or social conglomerates, as well as the relative independence of the supraorganismic systems, with the general physicochemical unity of the living matter of the biosphere.

The system of biological disciplines includes the direction of research on systematic objects: microbiology, zoology, botany, the doctrine of man, etc. The broadest regularities that reveal the essence of life, its forms and patterns of development are considered by general biology. This area of \u200b\u200bknowledge traditionally includes the doctrine of the origin of life on Earth, the doctrine of the cell, the individual development of organisms, molecular biology, Darwinism (evolutionary doctrine), genetics, ecology, the doctrine of the biosphere and the doctrine of man.

The emergence of life on earth.

The problem of the origin of life on Earth was and remains the main problem, along with cosmology and knowledge, to find the structure of matter. Modern science has no direct evidence of how and where life originated. There are only logical constructions and indirect evidence obtained through model experiments, and data in the field of paleontology, geology, astronomy, etc.

In scientific biology, the most famous hypotheses of the origin of life on Earth are S. Arrhenius's theory of panspermia and the theory of the origin of life on Earth as a result of a long evolutionary development of matter proposed by A.I. Oparin.

The theory of panspermia was widespread in the late 19th and early 20th centuries. And now it has many supporters.

According to this theory, living things were brought to Earth from outer space. Especially widespread were the assumptions of the transfer of the embryos of living organisms to the Earth with meteorites or cosmic dust. Until now, they are trying to find out what signs of living things in meteorites. In 1962, American scientists, in 1982, Russian scientists reported the discovery of the remains of organisms in meteorites. But it was soon shown that the found structural formations are actually mineral granules and only in appearance resemble biological structures. In 1992, the works of American scientists appeared, where they, on the basis of a study of material collected in Antarctica, describe the presence in meteorites of the remains of living creatures resembling bacteria. Time will tell what awaits this discovery. But, interest in the theory of panspermia has not faded to this day.

The beginning of the systematic development of the problem of the origin of life on Earth was laid in the 20s of our century. In 1924 A. I. Oparin's book "The Origin of Life" was published and in 1929 D. Haldane's article on the same topic. But, as Haldane himself later noted, it was hardly possible to find anything new in his article that Oparin did not have. Therefore, the theory of the origin of life on Earth as a result of the "biological big bang" can be safely called the Oparin theory, and not the Oparin-Haldane theory.

According to Oparin's theory, life originated on Earth. This process consisted of the following stages: 1) Organic substances are formed from inorganic substances; 2) there is a rapid physical and chemical restructuring of primary organic substances. Mirror asymmetric organic prebiological substances under conditions of active volcanic activity, high temperature, radiation, enhanced ultraviolet radiation, and thunderstorms quickly. During the polymerization of levorotatory amino acids, primary proteins were formed. At the same time, nitrogenous bases - nucleotides - appeared; 3) physicochemical processes contributed to the formation of coacervate drops (coacervates) - gel-type structures; 4) the formation of polynucleotides - DNA and RNA and their inclusion in coacervates; 5) the formation of a "film" that separated the coacervates from the environment, which led to the emergence of a prebiological system, which was an open system. It had the ability to matrix protein synthesis and degradation.

In subsequent years, Oparin's theory was fully confirmed. The great advantage of theory is that much of it can be tested or logically linked to verifiable propositions.

An extremely important step in the process of the emergence of life was the transition of inorganic carbon compounds to organic ones. Astronomical data have shown that even now the formation of organic substances is taking place everywhere, completely independently of life. From this it was concluded that such a synthesis took place on Earth during the formation of the Earth's crust. The beginning of a series of works on the synthesis was laid in 1953 by S. Miller, who synthesized a number of amino acids by passing an electric discharge through a mixture of gases, presumably constituting the primary atmosphere (hydrogen, water vapor, ammonia, methane). By changing individual components and influencing factors, various scientists obtained glycine, ascarginic acid and other amino acids. In 1963, by simulating the conditions of the ancient atmosphere, scientists obtained individual polypeptides with a molecular weight of 3000-9000. In recent years, the Institute of Biochemistry of the Russian Academy of Sciences and Moscow State University have studied in detail the chemical composition, physicochemical properties, and the mechanism of formation of coacervate drops. It was shown that simultaneously with the general process of evolution of prebiological systems, their transformation into more specialized structures took place.

And here it becomes clear that natural selection should lead in the future to the emergence of a cell - an elementary structural and functional unit of a living organism.

The main signs of the living.

The ability to move. Signs visually appearing in animals, many of which are able to actively move. In the simplest organs of movement are flagella, cilia, etc. In more organized animals limbs appear. Plants are also characterized by the ability to move. The unicellular algae Chlamydomonas has flagella. Dispersion of spores, spreading seeds, movement in space with the help of rhizomes are all variants of movement.

The ability to grow. All living things are capable of increasing in size and mass due to stretching, cell division, etc.

Nutrition, breathing, excretion are the processes by which metabolism is provided.

Irritability is the ability to react and respond to external influences.

Reproduction and the associated phenomenon of variability and heredity is the most characteristic feature of a living thing. Any living organism produces its own kind. The offspring retain the characteristics of the parents and acquire the characteristics that are characteristic only of them.

The totality of the listed signs undoubtedly characterizes the living as a system that forms metabolism, irritability and the ability to reproduce, but it should be remembered that the concept of living is much more complicated (see, introduction).

Levels of life organization.

The level of organization is the functional place of the biological structure of a certain degree of complexity in the general "system of systems" of the living. Usually, molecular (molecular genetic), cellular, organismic, population-specific, biocenotic, and biospheric levels of organization are distinguished.

The elementary and functional unit of life is the cell. The cell has almost all the basic characteristics of living things, in contrast to the so-called non-cellular organisms (eg viruses), which exist at the molecular level.

An organism is a real carrier of life, characterized by all of its bioproperties.

A species is a group of individuals similar in structure and origin.

A biocenosis is an interconnected set of species that inhabit a more or less homogeneous area of \u200b\u200bland or water body.

The biosphere is the totality of all biocenoses of the Earth.

Methods for studying biology.

The methods of modern biology are determined by its tasks. One of the main tasks of biology is the knowledge of the world of living beings around us. The methods of modern biology are aimed precisely at studying this problem.

Scientific research usually begins with observation. This method of studying biological objects has been used since the beginning of a meaningful human existence. This method allows you to create an idea of \u200b\u200bthe object under study, to collect material for further work.

Observation was the main method in the descriptive period of the development of biology. A hypothesis is put forward on the basis of observations.

The next steps in the study of biological objects are associated with experiment.

It became the basis for the transition of biology from a descriptive science to an experimental one. The experiment allows you to check the results of observations and obtain data that cannot be obtained at the first stage of the study.

A real scientific experiment must be accompanied by a control experiment.

The experiment must be reproducible. This will allow obtaining reliable data and processing the data using a computer.

In recent years, the modeling method has been widely used in biology. The creation of mathematical models of phenomena and processes became possible with the widespread introduction of computers in biological research.

An example is the algorithm for studying the species of a plant. At the first stage, the researcher examines the signs of the organism. The observation results are recorded in a special journal. Based on the identification of all available signs, a hypothesis is put forward about the belonging of an organism to a certain species. The correctness of the hypothesis is determined by experiment. Knowing that representatives of one species freely interbreed and give fertile offspring, the researcher grows an organism from seeds taken from the individual under study and crosses the grown organism with a reference organism, the species belonging of which is established in advance. If, as a result of this experiment, seeds are obtained from which a viable organism develops, then the hypothesis is considered confirmed.

The diversity of the organic world.

The diversity, as well as the diversity of life on Earth, is studied by taxonomy - the most important branch of biology.

The diversity of life on Earth is reflected in the systems of organisms. Representatives of three groups of organisms live on Earth: viruses, prokaryotes, eukaryotes.

Viruses are organisms that do not have a cellular structure. Prokaryotes and eukaryotes are organisms, the main structural unit of which is the cell. Prokaryotic cells do not have a formed cell nucleus. In eukaryotes, the cell has a real nucleus, where nuclear material is separated from the cytoplasm by a two-membrane membrane.

Prokaryotes include bacteria and blue-green algae. Bacteria are unicellular, in the bulk of heterozygous organisms. Blue-green algae are single-celled, colonial or multicellular organisms with a mixed diet. Blue-green cells contain chlorophyll, which provides autotrophic nutrition, but blue-green ones can absorb ready-made organic substances from which they build their own high-molecular substances. Within eukaryotes, three kingdoms are distinguished: fungi, plants, animals. Fungi are heterotrophic organisms whose body is represented by mecelium. Lichens form a special group of fungi, where unicellular or blue-green algae are symbionts of fungi.

Plants are primarily autotrophic organisms.

Animals are heterozygous eukaryotes.

Living organisms on Earth exist in a state of communities - biocenoses.

The very attitude of viruses to organisms is debatable, since they cannot multiply outside the cell and do not have a cellular structure. Still, most biologists believe that viruses are the smallest living organisms.

The Russian botanist D.I.Ivanovsky is considered the discoverer of viruses, but only with the invention of the electron microscope it became possible to study the structure of these mysterious structures. Viruses are very simple. The "core" of the virus is a DNA or RNA molecule. This "core" is surrounded by a protein envelope. Some viruses develop a lipoprotein envelope that arises from the cytoplasmic membrane of the host cell.

Once inside the cell, viruses acquire the ability to self-replicate. At the same time, they "turn off" the host's DNA and using their nucleic acid, give the command to synthesize new copies of the virus. Viruses can "attack" cells of all groups of organisms. Viruses that "attack" bacteria have received a special name - bacteriophages.

The importance of viruses in nature is related to their ability to cause various diseases. This is a mosaic of leaves, influenza, smallpox, measles, polio, mumps and the "plague" of the twentieth century - AIDS.

The method of transmission of viruses is carried out by droplets, by contact, with the help of carriers (fleas, rats, mice, etc.), through feces and food.

Acquired Immune Deficiency Syndrome (AIDS). AIDS virus.

AIDS is an infectious disease caused by an RNA virus. The AIDS virus is rod-shaped or oval or round in shape. In the latter case, its diameter reaches 140 nm. The virus consists of RNA, a revartase enzyme, two types of proteins, two types of glycoproteins and lipids that form the outer membrane. The enzyme catalyzes the synthesis reaction of a DNA strand along the viral RNA template in a virus-infected cell. The AIDS virus is expressed towards T-lymphocytes.

The virus is unstable to the environment, sensitive to many antiseptics. The infectious activity of the virus decreases 1000 times when warmed up at a temperature of 56C for 30 minutes.

The disease is transmitted sexually or through blood. Infection with AIDS is usually fatal!

Fundamentals of Cytology.

The main provisions of the cell theory.

The cage was discovered in the second half of the 17th century. The study of the cell developed especially strongly in the second half of the 19th century in connection with the creation of the cell theory. The cellular level of research has become the guiding principle of the most important biological disciplines. A new section has taken shape in biology - cytology. The object of study of cytology is the cells of multicellular organisms, as well as organisms, the body of which is represented by one cell. Cytology studies the structure, chemical composition, ways of their reproduction, adaptive properties.

The theoretical basis of cytology is the cell theory. The cell theory was formulated in 1838 by T. Schwann, although the first two provisions of the cell theory belong to M. Schleiden, who studied plant cells. T. Schwann, a well-known specialist in the structure of animal cells in 1838, based on the data of M. Schleiden's works and the results of his own research, made the following conclusions:

The cell is the smallest structural unit of living organisms.

Cells are formed as a result of the activity of living organisms.

Animal and plant cells have more similarities than differences.

The cells of multicellular organisms are structurally and functionally related.

Further study of the structure and life activity made it possible to learn a lot about it. This was facilitated by the perfection of microscopic technology, research methods and the arrival of many talented researchers in cytology. The structure of the nucleus was studied in detail, a cytological analysis of such important biological processes as mitosis, meiosis, fertilization was carried out. The microstructure of the cell itself has become known. Cell organelles have been discovered and described. The cytological research program of the 20th century set the task of finding out and more accurately distinguishing the properties of the cell. Hence, special attention was paid to the study of the chemical composition of the cell and the mechanism of absorption by the cell of substances by the environment.

All these studies have made it possible to multiply and expand the provisions of the cellular theory, the main postulates of which are currently as follows:

The cell is the basic and structural unit of all living organisms

Cells are formed only from cells as a result of division.

The cells of all organisms are similar in their structure, chemical composition, and basic physiological functions.

The cells of multicellular organisms form a single functional complex.

The cells of higher plants and animals form functionally related groups - tissues; the organs that make up the body are formed from tissues.

Features of the structure of cells of prokaryotes and eukaryotes.

Prokaryotes are the oldest organisms that form an independent kingdom. Prokaryotes include bacteria, blue-green "algae" and a number of other small groups.

Prokaryotic cells do not have a well-defined nucleus. The genetic apparatus is presented. consists of circular DNA. Mitochondria and the Golgi apparatus are absent in the cell.

Eukaryotes are organisms with a real nucleus. Eukaryolts include representatives of the plant kingdom, the animal kingdom, and the mushroom kingdom.

Eukaryotic cells are usually larger than prokaryotic cells and are divided into separate structural elements. DNA bound to protein forms chromosomes, which are located in the nucleus, surrounded by a nuclear envelope and filled with karyoplasm. The division of eukaryotic cells into structural elements is carried out using biological membranes.

Eukaryotic cells. Structure and function.

Eukaryotes include plants, animals, and fungi.

The structure of cells of plants and fungi is discussed in detail in the section of botany "Aids for applicants to universities" Compiled by MA Galkin.

In this manual, we will point out the distinctive features of animal cells, based on one of the provisions of cell theory. "There are more similarities than differences between plant and animal cells."

There is no cell wall in animal cells. It is represented by a naked protoplast. The boundary layer of the animal cell - the glycocalyx - is the upper layer of the cytoplasmic membrane "reinforced" by polysaccharide molecules that are part of the intercellular substance rather than the composition of the cell.

Mitochondria have folded cristae.

In animal cells, there is a cell center consisting of two centrioles. This suggests that any animal cell is potentially capable of division.

The inclusion in the animal cell is presented in the form of grains and drops (proteins, fats, carbohydrate glycogen), end products of metabolism, crystals of salts, pigments.

In animal cells, there may be small contractile, digestive, excretory vacuoles.

The cells have no plastids, inclusions in the form of starch grains, grains, large vacuoles filled with juice.

Cell division.

A cell is formed only from a cell as a result of division. Eukaryotic cells divide by the type of mitosis or the type of meiosis. Both of these divisions proceed in three stages:

The division of plant cells by the type of mitosis and by the type of meiosis is described in detail in the "Botany" section of the manual for university applicants compiled by MA Galkin.

Here we will indicate only the features of division for animal cells.

The features of division in animal cells are associated with the absence of a cell wall in them. During cell division by the type of mitosis in cytokinesis, the separation of daughter cells occurs already at the first stage. In plants, daughter cells are formed under the protection of the cell wall of the mother cell, which is destroyed only after the appearance of the primary cell wall in the daughter cells. When a cell is divided by the type of meiosis in animals, division occurs already in telophase 1. In plants, in telophase 1, the formation of a binuclear cell ends.

The formation of a division spindle in telophase one is preceded by the divergence of centrioles to the poles of the cell. The formation of spindle threads begins from the cenrioles. In plants, the spindle threads begin to form from the pole clusters of microtubules.

Cell movement. Organelles of movement.

Living organisms consisting of one cell often have the ability to actively move. The mechanisms of motion that have arisen in the process of evolution are very diverse. The main forms of movement are - amoeboid and with the help of flagella. In addition, cells can move by excreting mucus or by moving the main substance of the cytoplasm.

The amoeboid movement got its name from the simplest organism - the amoeba. The organs of movement in the amoeba are false legs - pseudosimilarities that are protrusions of the cytoplasm. They are formed in different places on the surface of the cytoplasm. They can disappear and appear in another place.

Movement with the help of flagella is typical for many unicellular algae (for example, Chlamydomonas), protozoa (for example, euglena green) and bacteria. The organs of movement in these organisms are flagella - cytoplasmic outgrowths on the surface of the cytoplasm.

The chemical composition of the cell.

The chemical composition of a cell is closely related to the features of the structure and functioning of this elementary and functional unit of the living.

As well as morphologically, the most common and universal for the cells of representatives of all kingdoms is the chemical composition of the protoplast. The latter contains about 80% water, 10% organic matter and 1% salt. The leading role in the formation of the protoplast among them is primarily proteins, nucleic acids, lipids and carbohydrates.

In terms of the composition of chemical elements, the protoplast is extremely complex. It contains substances with both low molecular weight and substances with a large molecule. 80% of the weight of the protoplast is high molecular weight and only 30% is low molecular weight compounds. At the same time, for each macromolecule there are hundreds, and for each large macromolecule there are thousands and tens of thousands of molecules.

If we consider the content of chemical elements in the cell, then the first place should be given to oxygen (65-25%). Next come carbon (15-20%), hydrogen (8-10%) and nitrogen (2-3%). The number of other elements, and there are about a hundred of them in cells, is much less. The composition of chemical elements in a cell depends both on the biological characteristics of the organism and on the habitat

Inorganic substances and their role in the life of the cell.

The inorganic substances of the cell include water and salts. For vital processes, of the cations that make up the salts, the most important are K, Ca, Mg, Fe, Na, NH, from the anions NO, HPO, HPO.

To plant cells, ammonium and nitrate ions are reduced to NH and are included in the synthesis of amino acids; In animals, amino acids are used to build their own proteins. When organisms die off, they are included in the cycle of substances in the form of free nitrogen. They are part of proteins, amino acids, nucleic acids and ATP. If phosphorus-phosphates, being in the soil, are dissolved by the root secretions of plants and absorbed. They are part of all membrane structures, nucleic acids and ATP, enzymes, and tissues.

Potassium is contained in all cells in the form of K ions. The "potassium pump" of the cell facilitates the penetration of substances through the cell membrane. It activates the processes of vital activity of cells, excitations and impulses.

Calcium is found in cells in the form of ions or salt crystals. Part of the blood contributes to its coagulation. It is part of the bones, shells, calcareous skeletons of coral polyps.

Magnesium is found in the form of ions in plant cells. Part of chlorophyll.

Iron ions are part of the hemoglobin contained in erythrocytes, which provide oxygen transport.

Sodium ions are involved in the transport of substances through the membrane.

The first place among the substances that make up the cell is water. It is contained in the basic substance of the cytoplasm, in the cell juice, in the karyoplasm, in the organelles. It enters into reactions of synthesis, hydrolysis and oxidation. It is a universal solvent and oxygen source. Water provides turgor, regulates osmotic pressure. Finally, it is an environment for physiological and biochemical processes in the cell. With the help of water, substances are transported through the biological membrane, the process of thermoregulation, and so on.

Water with other components - organic and inorganic, high molecular weight and low molecular weight - participates in the formation of the protoplast structure.

Organic substances (proteins, carbohydrates, lipids, nucleic acids, ATP), their structure and role in the life of the cell.

The cell is the elementary structure in which all the main stages of biological metabolism are carried out and all the main chemical components of living matter are contained. 80% of the protoplast weight is made up of high-molecular substances - proteins, carbohydrates, lipids, nucleic acids.

Among the main components of protoplasm, the leading role belongs to the protein. The protein macromolecule has the most complex composition and structure, and is characterized by an extremely rich manifestation of chemical and physicochemical properties. It contains one of the most important properties of living matter - biological specificity.

Amino acids are the main structural element of a protein molecule. The molecules of most amino acids contain one carboxyl and one amine group. Amino acids in a protein are linked to each other through peptide bonds due to carboxyl and - amine groups, that is, a protein is a polymer, the monomer of which is amino acids. Proteins of living organisms are formed by twenty "golden" amino acids.

A set of peptide bonds, which unites a chain of amino acid residues, forms a peptide chain - a kind of backbone of polypeptide molecules.

In a protein macromolecule, several orders of structure are distinguished - primary, secondary, tertiary. The primary structure of a protein is determined by the sequence of amino acid residues. The secondary structure of polypeptide chains is a continuous or discontinuous helix. The spatial orientation of these helices or the collection of several polypeptides constitute a higher-order system - a tertiary structure characteristic of the molecules of many proteins. For large protein molecules, such structures are only subunits, the relative spatial arrangement of which makes up a quaternary structure.

Physiologically active proteins have a globular structure such as a coil or cylinder.

The amino acid sequence and structure determine the properties of the protein, and the properties determine the function. There are proteins that are not soluble in water, but there are proteins that are freely soluble in water. There are proteins soluble only in weak alkali solutions or 60-80% alcohol. Proteins also differ in molecular weight, and hence in the size of the polypeptide chain. A protein molecule under the influence of certain factors is capable of rupture or unwinding. This phenomenon is called denaturation. The denaturation process is reversible, i.e., the protein is able to change its properties.

The functions of proteins in the cell are varied. These are primarily building functions - the protein is part of the membranes. Proteins act as catalysts. They speed up metabolic reactions. Cellular catalysts are called enzymes. Proteins also perform a transport function. A prime example is hemoglobin, an oxygen transfer agent. The protective function of proteins is known. Let us recall the formation of substances in cells that bind and neutralize substances that can harm the cell. Although insignificant, proteins have an energetic function. By breaking down into amino acids, they release energy.

About 1% of the dry matter of the cell is carbohydrates. Carbohydrates are classified into simple sugars, low molecular weight carbohydrates, and high molecular weight sugars. All types of carbohydrates contain carbon, hydrogen and oxygen atoms.

Simple sugars, or monoses, are divided into pentoses and heptoses according to the number of carbon units in the molecule. Of the low molecular weight carbohydrates in nature, the most widespread are sucrose, maltose, and lactose. High molecular weight carbohydrates are divided into simple and complex. The simple ones include polysaccharides, the molecules of which consist of the residues of any one monose. These are starch, glycogen, cellulose. The complex includes pectin, mucus. Apart from monoses, complex carbohydrates contain products of their oxidation and reduction.

Carbohydrates perform a building function, forming the basis of the cell wall. But the main function of carbohydrates is energy. When complex carbohydrates are broken down to simple ones, and simple ones to carbon dioxide and water, a significant amount of energy is released.

All cells of animals and plants contain lipids. Lipids include substances of various chemical nature, but possessing general physical and chemical properties, namely: Insolubility in water and good solubility in organic solvents - ether, benzene, gasoline, chloroform.

According to their chemical composition and structure, lipids are subdivided into phospholipids, sulfolipids, sterols, fat-soluble pigments, fats and waxes. Lipid molecules are rich in hydrophobic radicals and groups.

The building function of lipids is great. The bulk of biological membranes are lipids. During the breakdown of fats, a large amount of energy is released. Some vitamins (A, D) belong to lipids. Lipids have a protective function in animals. They are deposited under the skin, creating a layer of low thermal conductivity. In a camel, fat is a source of water. One kilogram of fat, being oxidized, gives one kilogram of water.

Nucleic acids, like proteins, play a leading role in the metabolism and molecular organization of living matter. They are associated with protein synthesis, cell growth and division, the formation of cell structures, and, consequently, the formation and heredity of the organism.

Nucleic acids contain three main structural elements: phosphoric acid, a pentose-type carbohydrate, and nitrogenous bases; connecting they form nucleotides. Nucleic acids are polynucleotides, i.e., polymerization products of a large number of nucleotides. In nucleotides, structural elements are linked in the following sequence: phosphoric acid - pentose - nitrogenous base. At the same time, pentose is associated with phosphoric acid with an ether bond, with a base - with a glucoside bond. The bond between nucleotides in a nucleic acid is carried out through phosphoric acid, the free radicals of which determine the acidic properties of nucleic acids.

In nature, there are two types of nucleic acids - ribonucleic acid and deoxyribonuleic acid (RNA and DNA). They differ in the carbon component and the set of nitrogenous bases.

RNA contains ribose as a carbon component, DNA contains deoxyribose.

The nitrogenous bases of nucleic acids are purine and pyramidine derivatives. The former include adenine and guanine, which are essential components of nucleic acids. Pyramidine derivatives are cytosine, thymine, uracil. Of these, only cytosine is required for both nucleic acids. As for thymine and uracil, the former is characteristic of DNA, the latter is characteristic of RNA. Depending on the presence of a nitrogenous base, nucleotides are called adenine, cytosyl, guanine, thymine, uracil.

The structural structure of nucleic acids became known after the greatest discovery made in 1953 by Watson and Crick.

A DNA molecule consists of two spirally running polynucleotide chains twisted around a common axis. These chains face each other with nitrogenous bases. The latter hold both chains together throughout the molecule. Only two combinations are possible in the DNA molecule: adenine with thymine, and guanine with cytosine. In the course of the spiral, two "grooves" are formed in the macromolecule - one small one located between two polynucleotide chains, the other large one representing the opening between the turns. The distance between base pairs along the axis of the DNA molecule is 3.4 A, 10 nucleotide pairs are laid in one spiral turn, respectively, the length of one turn is 3.4 A. The cross-sectional diameter of the spiral is 20 A. DNA in eukaryotes is contained in the cell nucleus, where is a part of chromosomes, and in the cytoplasm, where it is found in mitochondria and chloroplasts.

A special property of DNA is its ability to double - this process of self-reproduction will determine the transfer of hereditary properties from the mother cell to the daughter.

DNA synthesis is preceded by the transition of its structure from double-stranded to single-stranded. After that, on each polynucleotide chain, as on a template, a new polynucleotide chain is formed, the nucleotide sequence in which corresponds to the original one, such a sequence is determined by the principle of base complementarity. Against each A stands T, against C - G.

Ribonucleic acid (RNA) is a polymer whose monomers are ribonucleotides: adenine, cytosine, guanine, uracil.

Currently, there are three types of RNA - structural, soluble or transport, informational. Structural RNA is found mainly in ribosomes. Therefore, it is called ribosomal RNA. It constitutes up to 80% of the total RNA of a cell. Transport RNA consists of 80-80 nucleotides. It is part of the basic substance of the cytoplasm. It makes up approximately 10-15% of all RNA. It plays the role of a carrier of amino acids into the ribosomes, where protein synthesis is carried out. Messenger RNA is highly heterogeneous; it can have a molecular weight of 300,000 to 2 million or more and has an extremely high metabolic activity. Messenger RNA is continuously formed in the nucleus on DNA, which plays the role of a matrix, and is sent to the ribosome where it participates in protein synthesis. In this regard, messenger RNA is called messenger RNA. It is 10-5% of the total RNA.

Adenine triphosphoric acid occupies a special place among the organic substances of the cell. It contains three known components: the nitrogenous base adenine), carbohydrate (ribose), and phosphoric acid. A feature of the structure of ATP is the presence of two additional phosphate groups attached to the already existing phosphoric acid residue, as a result of which energy-rich bonds are formed. Such connections are called macroenergetic. One macroenergy bond in a gram-molecule of a substance contains up to 16,000 calories. ATP and ADP are formed in the process of respiration due to the energy released during the oxidative breakdown of carbohydrates, fats, etc. The reverse process, that is, the transition from ATP to ADP, is accompanied by the release of energy, which is directly used in certain life processes - in synthesis substances, in the movement of the basic substance of the cytoplasm, in the conduction of excitations, etc. ATP is a single and universal source of energy supplying source of the cell. As it became known in recent years, ATP and ADP, AMP are the starting material for the formation of nucleic acids.

Regulatory and signaling substances.

Proteins have many wonderful properties.

Enzymes. Most of the reactions of assimilation and dissimilation in the body are carried out with the participation of enzymes - proteins that are biological catalysts. Currently, about 700 enzymes are known to exist. They are all simple or complex proteins. The latter are composed of protein and coenzyme. Coenzymes are various physiologically active substances or their derivatives - nucleotides, flavins, etc.

Enzymes are extremely active, which largely depends on the pH of the medium. For enzymes, their specificity is most characteristic. Each enzyme is capable of regulating only a strictly defined type of reaction.

Thus, enzymes function as accelerators and regulators of almost all biochemical processes in the cell and in the body.

Hormones are the secrets of the endocrine glands. Hormones provide the synthesis of certain enzymes in the cell, activate or inhibit their work. Thus, they accelerate the growth of the body and cell division, enhance muscle work, and regulate the absorption and excretion of water and salts. The hormonal system, together with the nervous system, ensures the activity of the body as a whole, through the special action of hormones

Vitamins. Their biological role.

Vitamins are organic substances formed in the animal body or supplied with food in very small quantities, but absolutely necessary for normal metabolism. Lack of vitamins leads to the disease of hypo- and avitaminosis.

More than 20 vitamins are currently known. These are B vitamins, vitamins E, A, K, C, PP, etc.

The biological role of vitamins is that, in their absence or deficiency, the work of certain enzymes is disrupted, biochemical reactions and normal cell activity are disrupted.

Protein biosynthesis. Genetic code.

The biosynthesis of proteins, or rather polypeptide chains, is carried out on ribosomes, but this is only the final stage of a complex process.

DNA contains information about the structure of the polypeptide chain. A piece of DNA that carries information about the polypeptide chain is a gene. When this became known, it became clear that the DNA nucleotide sequence should determine the amino acid sequence of the polypeptide chain. This relationship between bases and amino acids is known as the genetic code. As you know, a DNA molecule is built of four types of nucleotides, which include one of four bases: adenine (A), guanine (G), thymine (T), cytosine (C). The nucleotides are linked into a polynucleotide chain. This four-letter alphabet provides instructions for synthesizing a potentially infinite number of protein molecules. If one base determined the position of one amino acid, then the chain would contain only four amino acids. If each amino acid were encoded with two bases, then using such a code, 16 amino acids could be encrypted. Only a code consisting of triplets (triplet code) can ensure that all 20 amino acids are included in the polypeptide chain. This code includes 64 different triplets. The genetic code is now known for all 20 amino acids.

The main features of the genetic code can be formulated as follows.

The code that determines the inclusion of an amino acid in the polypeptide chain is a triplet of bases in the polypeptide DNA chain.

The code is universal: the same triplets encode the same amino acids in different microorganisms.

The code is degenerate: a given amino acid can be encoded by more than one triplet. For example, the amino acid leucine is encoded by triplets GAA, GAG, GAT, GAC.

Overlapping code: for example, the nucleotide sequence AAACAATTA is only read as AAA / CAA / TTA. It should be noted that there are triplets that do not encode an amino acid. The function of some of these triplets has been established. These are start codons, reset codons, etc. The functions of others require decoding.

The sequence of bases in one gene, which carries information about the polypeptide chain, “is rewritten in its complementary sequence of bases of messenger or messenger RNA. This process is called transcription, the I-RNA molecule is formed as a result of free ribonucleotides binding to each other under the action of RNA - lymerase in accordance with the rules of DNA and RNA base pairing (A-U, G-C, T-A, C-G). The synthesized I-RNA molecules, carrying genetic information, leave the nucleus and go to the ribosomes. Here, a process called translation takes place - the sequence of base triplets in the I-RNA molecule is translated into a specific sequence of amino acids in the polypeptide chain.

Several ribosomes are attached to the end of the DNA molecule to form a polysome. This entire structure is a series-connected ribosome. In this case, the synthesis of several polypeptide chains can be carried out on one I-RNA molecule. Each ribosome consists of two subunits - small and large. I-RNA Attaches to the surface of the small subunit in the presence of magnesium ions. In this case, its first two translated codons turn out to be directed to the large subunit of the ribosome. The first codon binds the t_RNA molecule containing the complementary anticodon and carrying the first amino acid of the synthesized polypeptide. Then the second anticodon attaches an amino acid-t-RNA complex containing an anticodon complementary to this codon.

The function of the ribosome is to keep the i-RNA, t-RNA and protein factors involved in the translation process in the desired position until a peptide bond is formed between adjacent amino acids.

Once a new amino acid has joined the growing polypeptide chain, the ribosome moves along the i-RNA strand in order to put the next codon in place. The t-RNA molecule, which was previously bound to the polypeptide chain, has now been freed from the amino acid, leaves the ribosome and returns to the main substance of the cytoplasm to form a new amino acid-t-RNA complex. This sequential "reading" of the "text" contained in the mRNA by the ribosome continues until the process reaches one of the stop codons. These codons are the UAA, UAG, or UGA triplets. At this stage, the polypeptide chain, the primary structure of which was encoded in the DNA region - the gene, leaves the ribosome and translation is complete.

Once the polypeptide chains are detached from the ribosome, they can acquire their characteristic secondary, tertiary, or quaternary structure.

In conclusion, it should be noted that the entire process of protein synthesis in the cell is with the participation of enzymes. They provide the synthesis of i-RNA, the "capture" of amino acids of t-RNA, the combination of amino acids into a polypeptide chain, the formation of a secondary, tertiary, quaternary structure. It is because of the participation of enzymes that protein synthesis is called biosynthesis. To ensure all stages of protein synthesis, the energy released during the breakdown of ATP is used.

Regulation of transcription and translation (protein synthesis) in bacteria and higher organisms.

Each cell contains a complete set of DNA molecules. With information about the structure of all polypeptide chains that can only be synthesized in a given organism. However, in a certain cell only part of this information is realized. How is this process regulated?

Currently, only individual mechanisms of protein synthesis have been elucidated. Most enzyme proteins are formed only in the presence of substrate substances on which they act. The structure of the enzyme protein is encoded in the corresponding gene (structural gene). Next to the structural gene is another operator gene. In addition, the cell contains a special substance - a repressor, capable of interacting with both the operator gene and the substrate substance. Repressor synthesis is regulated by a regulator gene.

By attaching to the operator gene, the repressor interferes with the normal functioning of the structural gene adjacent to it. However, when it binds to the substrate, the repressor loses its ability to bind to the operator gene and interfere with the synthesis of i-RNA. The formation of the repressors themselves is controlled by special regulator genes, the functioning of which is controlled by second-order repressors. That is why not all, but only specific cells react to a given substrate by synthesizing an appropriate enzyme.

On this, however, the hierarchy of repressor mechanisms is not interrupted, there are repressors of higher orders, which indicates the amazing complexity associated with the start of the gene in the cell.

The reading of the "text" enclosed in i-RNA stops when this process reaches the stop codon.

Autotrophic (autotrophic) and heterotrophic organisms.

Autotrophic organisms synthesize organic substances from inorganic substances using the energy of the Sun or the energy released during chemical reactions. The former are called heliotrophs, the latter are called chemotrophs. Plants and some bacteria are autotrophic organisms.

In nature, there is also a mixed type of food, which is characteristic of some bacteria, algae and protozoa. Such organisms can synthesize organic substances in their bodies from ready-made organic substances and from inorganic ones.

The volume of substances in the cell.

The volume of substances is the process of successive consumption, transformation, use, accumulation of the loss of substances and energy that allows the cell to preserve itself, grow, develop and multiply. Metabolism consists of continuous processes of assimilation and dissimilation.

Plastic exchange in the cell.

Plastic metabolism in a cell is a set of assimilation reactions, that is, the transformation of certain substances inside the cell from the moment they are received until the formation of final products - proteins, glucose, fats, etc. Each group of living organisms is characterized by a special, genetically fixed type of plastic metabolism.

Plastic metabolism in animals. Animals are heterotrophic organisms, that is, they eat food containing ready-made organic matter. In the intestinal tract or intestinal cavity, they are broken down: proteins to amino acids, carbohydrates to monoses, fats to fatty acids and glycerol. Cleavage products enter the bloodstream and directly into the cells of the body. In the first case, the cleavage products again end up in the cells of the body. In the cells, the synthesis of substances occurs, which is already characteristic of the given cell, i.e., a specific set of substances is formed. Of the reactions of plastic metabolism, the simplest are the reactions that ensure the synthesis of proteins. Protein synthesis occurs on ribosomes, according to information about the structure of the protein contained in DNA, from amino acids entered into the cell. The synthesis of di-, polysaccharides comes from monoses in the Golgi apparatus. Fats are synthesized from glycerin and fatty acids. All synthesis reactions take place with the participation of enzymes and require the expenditure of energy, energy for assimilation reactions is provided by ATP.

Plastic metabolism in plant cells has much in common with plastic metabolism in animal cells, but it has a certain specificity associated with the way of plant nutrition. Plants are autotrophic organisms. Plant cells containing chloroplasts are able to synthesize organic matter from simple inorganic compounds using light energy. This process, known as photosynthesis, allows plants to use chlorophyll from six molecules of carbon dioxide and six molecules of water to produce one molecule of glucose and six molecules of oxygen. Further, the conversion of glucose follows the path known to us.

Metabolites arising in plants in the course of metabolism give rise to the constituent elements of proteins - amino acids and fats - glycerol and fatty acids. Protein synthesis in plants is like animals on ribosomes, and fat synthesis in the cytoplasm. All plastic metabolic reactions in plants involve enzymes and ATP. As a result of plastic metabolism, substances are formed that ensure cell growth and development.

Energy metabolism in the cell and its essence.

The set of dissimilation reactions, accompanied by the release of energy, is called energy exchange. The most energetic substances are proteins, fats and carbohydrates.

Energy metabolism begins from the manufacturing stage, when proteins are broken down into amino acids, fats into glycerol and fatty acids, polysaccharides into monosaccharides. The energy generated at this stage is negligible and dissipates as heat. Of the substances formed, glucose is the main supplier of energy. The breakdown of glucose in the cell, which results in the synthesis of ATP, occurs in two stages. It all starts with anoxic breakdown - glycolysis. The second stage is called oxygen degradation.

Glycolysis is a sequence of reactions in which one glucose molecule breaks down into two pyruvic acid molecules. These reactions take place in the basic substance of the cytoplasm and do not require the presence of oxygen. The process takes place in two stages. At the first stage, glucose is converted into fructose –1, 6, -biphosphate, and at the second, the latter is split into two three-carbon sugars, which are later converted into pyruvic acid. At the same time, at the first stage, two ATP molecules are consumed in phosphorylation reactions. Thus, the net yield of ATP during glycolysis is two ATP molecules. In addition, four hydrogen atoms are released during glycolysis. The total glycolysis reaction can be written as follows:

CHO 2CHO + 4H + 2 ATP

Further, in the presence of oxygen, pyruvic acid passes into mitochondria for complete oxidation to CO and water (aerobic respiration). If there is no oxygen, then it turns either into ethanol or into lactic acid (anaerobic respiration).

Oxygen breakdown (aerobic respiration) occurs in the mitochondria, where, under the action of enzymes, pyruvic acid reacts with water and completely decomposes to form carbon dioxide and hydrogen atoms. Carbon dioxide is removed from the cell. Hydrogen atoms enter the mitochondrial membrane, where they are oxidized as a result of an enzymatic process. Electrons and hydrogen cations are transported by carrier molecules to opposite sides of the membrane: electrons to the inner membrane, protons to the outer membrane. Electrons combine with oxygen. As a result of these rearrangements, the membrane is charged positively from the outside and negatively from the inside. When the critical level of the potential difference across the membrane is reached, positively charged particles are pushed through the channel in the enzyme molecule built into the membrane to the inner side of the membrane, where they combine with oxygen to form water.

The oxygen breathing process can be represented as the following level:

2CHO + 6O + 36ADP + 36NRO 36ATF + 6CO + 42NO.

And the total equation of glycolysis and oxygen process looks like this:

CHO + 6O + 38ADP + 38NRO 38ATF + 6CO + 44NO

Thus, the splitting of one glucose molecule in the cell to carbon dioxide and water provides the synthesis of 38 ATP molecules.

This means that in the process of energy metabolism, ATP is formed - a universal source of energy in the cell.

Chemosynthesis.

Each organism, to maintain life and carry out processes, the totality of which constitutes metabolism, needs a constant flow of energy.

The process of formation of organic substances by some microorganisms from carbon dioxide due to the energy obtained during the oxidation of inorganic compounds (ammonia, hydrogen, sulfur compounds, ferrous iron) is called chemosynthesis.

Depending on the mineral compounds, as a result of the oxidation of which microorganisms, and these are mainly bacteria, are able to receive energy, chemoautotrophs are divided into nitrifying, hydrogen, sulfur bacteria, and iron bacteria.

Nitrophying bacteria oxidize ammonia to nitric acid. This process takes place in two phases. First, ammonia is oxidized to nitric acid:

2NH + 3O \u003d 2HNO + 2HO + 660 kJ.

Then nitrous acid is converted to nitric:

2HNO + O \u003d 2HNO + 158 kJ.

In total, 818 kJ are released, which are used for the utilization of carbon dioxide.

In iron bacteria, ferrous iron oxidation occurs according to the equation

Since the reaction is accompanied by a low energy yield (46.2 * 10 J / g of oxidized iron), bacteria have to oxidize a lot of iron to maintain growth.

When one molecule of hydrogen sulfide is oxidized, 17.2 * 10 J. are released, one sulfur molecule - 49.8 * 10 J., and one molecule - 88.6 * 10 J.

The chemosynthesis process was discovered in 1887 by S.N. Vinogradsky. This discovery not only shed light on the characteristics of metabolism in bacteria, but also made it possible to determine the significance of bacteria - chemoautotroph. This is especially true of nitrogen-fixing bacteria, which convert nitrogen inaccessible to plants into ammonia, which contributes to an increase in soil fertility. The process of participation of bacteria in the circulation of substances in nature also became clear.

Reproduction of organisms.

Reproduction forms of organisms.

The ability to reproduce, i.e. to produce a new generation of the same species, one of the main features of living organisms.

There are two main types of reproduction - asexual and sexual.

Asexual reproduction.

With asexual reproduction, offspring descend from one organism. Identical offspring originating from this parent is called a clone. The members of the same clone can be genetically different only in the case of random mutations. Asexual reproduction is not found only in higher animals. However, it is known that cloning has been successfully carried out for some species and higher animals - frogs, sheep, cows.

In the scientific literature, several forms of asexual reproduction are distinguished.

Division. Single-celled organisms reproduce by division: each individual is divided into two or more daughter cells, identical to the parent cell. This is how bacteria, amoeba, euglena, chlamydomonas, etc. multiply.

Dispute formation. A spore is a unicellular reproductive structure. Spore formation is characteristic of all plants and fungi.

Budding. Budding is a form of asexual reproduction, in which a new individual is formed in the form of an outgrowth on the body of the parent individual, and then separates from it and turns into an independent organism. Budding occurs in coelenterates and yeast.

Reproduction in fragments. Fragmentation is the division of an individual into several parts, which grows and forms a new individual. This is how spirogyra, lichens and some types of worms multiply.

Vegetative reproduction. This is a form of asexual reproduction, in which a relatively large, usually differentiated, part is separated from the plant and develops into an independent plant. This propagation is by bulbs, tubers, rhizomes, etc. Vegetative propagation is described in detail in the Botany section. (Botany. A guide for applicants to universities. Compiled by MA Galkin).

Sexual reproduction.

With sexual reproduction, offspring is obtained as a result of sexual reproduction - the fusion of the genetic material of the haploid nuclei. The nuclei are located in specialized sex cells - gametes. Gametes are haploid - they contain one set of chromosomes resulting from meiosis; they serve as a link between this generation and the next. Gametes can be the same in size and shape, with organs of movement - flagella or without them, but more often male gametes differ from female ones. Female gametes - eggs are usually larger than male ones, have a rounded shape and usually do not have locomotor organs. In oocytes, the elements of the protoplast are also clearly distinguished, like the nucleus. The main substance of the cytoplasm accumulates a large amount of nutrients. Male gametes have a significantly simplified structure. They are mobile, i.e. have flagella. These are sperm. There are sperm without flagella.

Sexual reproduction has enormous biological significance. During meiosis, when gametes are formed, as a result of random divergence of chromosomes and the exchange of genetic material between homologous chromosomes, new combinations of genes appear in one gamete, which increases genetic diversity.

During fertilization, the gametes merge, forming a diploid zygote - a cell containing one chromosome set from each gamete. This union of two sets of chromosomes constitutes the genetic basis for intraspecific variation.

Parthenogenesis.

One of the forms of sexual reproduction is parthenogenesis - in which the development of the embryo occurs from an unfertilized egg. Parthenogenesis is common among insects (aphids, bees), a variety of rotifers, protozoa, as an exception occurs in some lizards.

There are two types of parthenogenesis - haploid and diploid. In ants, as a result of haploid parthenogenesis within the community, various castes of organisms arise - soldiers, cleaners, etc. In bees from an unfertilized egg, drones appear in which spermatozoa are formed by mitosis. Aphids undergo diploid parthenogenesis. In them, during the formation of cells in anaphase - homologous chromosomes do not diverge - and the egg itself turns out to be diploid with three “sterile” polar bodies. In plants, parthenogenesis is fairly typical. Here it is called apomixis. As a result of "stimulation" in the egg, chromosomes are duplicated. A normal embryo develops from a diploid cell.

Plant taxonomy.

Taxonomy studies the diversity of plants. Systematic categories are the object of study of taxonomy. The main systematic categories are: species, genus, family, class, department, kingdom.

A species is a set of populations of individuals capable of interbreeding under natural conditions and forming fertile offspring. A genus is a collection of closely related species. A family is a collection of closely related genera. A class unites closely related families, a department - closely related classes. In this case, plants act as a kingdom.

The scientific names of all systematic categories are given in Latin. The names of the systematic categories above the species consist of one word. Binary names have been adopted for species since 1753 thanks to K. Linnaeus. The first word denotes a species, the second is a specific epithet. The names of systematic categories in Russian are rarely translated from Latin; more often these are original names born among the people.

The formation of germ cells in humans. The structure of human sex cells. Fertilization in humans. The biological significance of fertilization.

Spermatozoa - Male germ cells are formed as a result of a series of sequential cell divisions - spermatogenesis, followed by a complex differentiation process called spermatogenesis.

First, division of cells of the germinal epithelium, which is located in the seminiferous tubules, gives rise to spermatogonia, which increase in size and become first-order spermatocytes. As a result of the first division of meiosis, they form diploid spermatocytes of the second order, after the second division of meiosis, they give rise to spermatozoa. An adult sperm consists of a head, an intermediate section and a flagellum (tail). The head consists of an acrosome and a nucleus surrounded by a membrane. The neck has a centriole. Mitochondria are located in the intermediate section.

Ovum formation in humans - oogenesis proceeds in several stages. At the first stage, as a result of metotic division, oogonia are formed from the cells of the embryonic epithelium. Oogonia divide according to the type of mitosis and give rise to first-order oocytes. From oocytes of the first order, as a result of mitotic division, eggs and polar bodies are formed.

Fertilization in humans is internal. As a result of the penetration of the sperm into the egg, the nuclei of the sex cells merge. A zygote is formed.

As a result of fertilization, the diploid set of chromosomes is restored, a new organism is formed, bearing the characteristics of the mother and father. During the formation of germ cells, a recombination of genes occurs, so the new organism combines the best characteristics of the parents.

The individual development of an organism is ontogenesis.

Ontogenesis is the period of development of an organism from the first division of the zygote to natural death.

The development of the embryo (by the example of animals).

Regardless of where the development of the embryo takes place, the beginning of its development is associated with the first mitotic division. Cytokinesis following the division of the nucleus leads to the formation of two diploid daughter cells, which are called blastomeres. Blastomeres continue to divide according to the type of mitosis, with longitudinal division alternating with transverse division. Division of blastomeres is called cleavage, because during this process, no cell growth occurs, and the resulting lump of cells - morula in volume is equal to two primary blastomeres. Further development of the embryo is associated with the formation of blastula. In this case, the blastomeres form a single-layer wall around the central cavity filled with fluid. The cells of the blastula wall begin to divide at one of the sites and form an internal cell mass. Subsequently, the inner layer of the wall is formed from this cell mass, thus separating the ectoderm - the outer layer and endoderm - the inner layer of cells. This two-layer developmental stage is called gastrula. At a later stage in the development of the embryo, the mesoderm is formed - the third germ layer. Ectoderm, endoderm and mesoderm give rise to all tissues of the developing embryo. Ectoderm cells give rise to the first lamina, the first crest, and the ectoblast. Upward folds appear along the edge of the first plate, and in the central part, the neural groove, which deepens and turns into a neural tube, is the rudiment of the central nervous system. From the front of the neural tube, the brain and eye rudiments are formed. In the front part of the embryo, the rudiments of the organs of hearing and smell are formed from the ectoblast. Epiblast gives rise to the epidermis, hair, feathers, scales. The neural crest is transformed into the rudiments of the nerve substance of the spine and jaws. From the ectoderm, the primary intestine, internal epithelium, the rudiments of glands, etc. are formed. The mesoderm gives rise to the notochord, somites, mesechimes and nephrotomes. From somites, the rudiments of the dermis, muscles of the walls of the body, vertebrae, skeletal muscles develop. From the mesenchyme of the rudiments of the heart, smooth muscles, blood vessels and blood itself. Nephrotomas give rise to the uterus, adrenal cortex, ureters, etc.

During the development of the derivatives of the germ layers, the appearance of the embryo changes. It takes on a certain shape, reaches a certain size. The development of the embryo ends with hatching from an egg or the birth of a young.

Postembryonic development.

From the moment the embryo hatches from the egg or the baby is born, post-embryonic development begins. It can be direct, when a born organism is similar in structure to an adult, and indirect, when embryonic development leads to the development of a larva, which has morphological, anatomical and physiological differences from an adult. Direct development is typical for most vertebrates, which include reptiles, birds, mammals. Postembryonic development of these organisms is associated with simple growth, which already leads to qualitative changes - development.

Animals with indirect development include coelenterates, flukes, tapeworms, crustaceans, insects, molluscs, echinoderms, tunicates, amphibians.

Indirect development is also called development with metamorphosis. The term "metamorphosis" refers to rapid changes occurring from the larval stage to the adult form. The larvae usually serve as a stage intended for dispersal, that is, they ensure the spread of the species.

Larvae differ from an adult in their habitat, nutritional biology, mode of locomotion and behavior; due to this, the species can use the opportunities presented by two ecological types during ontogenesis, which increases its chances of survival. Many species, such as dragonflies, feed and grow only in the larval stage. The larvae play the role of a transitional stage, during which the species can adapt to new habitat conditions. In addition, the larvae sometimes possess physiological endurance, due to which, under unfavorable conditions, they act as a resting stage. For example, the May beetle overwinters in the soil in the form of a larva. But in most cases in insects this occurs at a different stage of metamorphosis - at the pupal stage.

Finally, the larval stages sometimes have the advantage that an increase in the number of larvae is possible at these stages. As it happens in some flatworms.

It should be noted that in many cases the larvae reach a very high organization, such as, for example, insect larvae, in which only the reproductive organs remain underdeveloped.

Thus, the structural and functional changes that occur during metamorphosis prepare the body for adulthood in a new habitat.

The biological clock. Self-regulation. The influence of various factors on the development of the body. Adaptation of the body to changing conditions, Anabiosis.

At all stages of development - the stage of the embryo, the stage of postembryonic development, the body is influenced by environmental factors - temperature, humidity, light, food resources, etc.

The organism is especially susceptible to the influence of environmental factors at the stage of the embryo and at the stage of postembryonic development. At the embryonic stage, when the organism develops in the mother's body and is connected to her by the circulatory system, the mother's behavior is decisive in its normal development. The mother smokes, the fetus also smokes. The mother drinks alcohol, "drinks alcohol" and the fetus. The embryo is especially susceptible to influence in 1-3 months of its development. A normal lifestyle during postembryonic development allows the body to exist normally until natural death. The organism is genotypically adapted to exist in a certain range of temperatures, humidity, salinity, and illumination. He needs a certain diet.

Walrusism, pedestrian crossings through Antarctica, space flights, starvation, gluttony will certainly lead to the development of a number of diseases.

A healthy lifestyle is the key to longevity.

All biological systems are characterized by a greater or lesser capacity for self-regulation. Self-regulation - the state of dynamic constancy of the natural system is aimed at maximum limiting the effects of the external and internal environment, preserving the relative constancy of the structure and functions of the body.

In addition, the influence of various factors on the body is smoothed out as a result of the formation of a complex system of physiological reactions in organisms to temporary - seasonal and especially to short-term - daily changes in environmental factors, which are displayed in the biological clock. An example is the clear preservation of flowering in plants at certain times of the day.

Anabiosis is a special type of adaptation of the organism to changing conditions - a temporary state of the organism, in which life processes are so slowed down that practically all visible manifestations of life are absent. The ability to fall into suspended animation contributes to the survival of organisms in sharply unfavorable conditions. Anabiosis is common in fungi, microorganisms, plants, animals. With the onset of favorable conditions, organisms that have fallen into suspended animation return to active life. Let us recall dried rotifers, cysts, spores, etc.

All adaptations of organisms to changing conditions are a product of the activity of natural selection. Natural selection also determined the amplitude of the action of environmental factors, which allows the body to exist normally.

Evolutionary process and its laws.

Preconditions for the emergence of the evolutionary theory of Charles Darwin.

The emergence of the evolutionary theory of Charles Darwin, which he outlined in the book "The Origin of Species", was preceded by a long development of biology, its functional and applied disciplines. Long before Charles Darwin, attempts were made to explain the apparent diversity of organisms. Various evolutionary hypotheses were put forward that could explain the similarities between animal organisms. It is worth mentioning here Aristotle, who as early as the 4th century BC. e. He formulated the theory of continuous and gradual development of living things from inanimate matter, created the idea of \u200b\u200bthe ladder of nature. In the late 18th century, John Ray created the concept of the species. And in 1771-78. K. Linnaeus has already proposed a system of plant species. Biology owes its further development to this scientist.

Works by K. Linnaeus.

During the heyday of K. Linnaeus, which falls in the middle of the 18th century, biology was dominated by a metaphysical concept of nature, based on immutability and initial expediency.

K. Linnaeus had at hand huge collections of plants and began to systematize them. Based on the doctrine of D. Rey about the species, he began to group plants within the scope of this category. During this period of activity, K. Linnaeus creates the language of botany: he defines the essence of a trait and groups traits into properties, creating cross-cutting diagnoses - a description of species. K. Linnaeus legalized the binary nomenclature of the species. Each species began to be named with two words in Latin. The first denotes a genus, the second is a specific epithet. Species descriptions were also carried out in Latin. This made it possible to make all descriptions available to scientists from all countries, since Latin was studied in all universities. An outstanding achievement of K. Linnaeus was the creation of a system of plants and the development of systematic categories. Based on the structure of the reproductive organs, C. Linnaeus combined all known plants into classes. The first 12 classes are distinguished by the number of stamens: class 1 - single-stamen, class 2 - double-stamen, etc. The 14th class included plants without flowers. He called these plants secret. Classes K. Linnaeus divided into families, based on the structure of the flower and other organs. From K. Linnaeus there are families as Compositae, Umbelliferae, Cruciferous, etc. K. Linnaeus divided families into genera. Rod K. Linnaeus considered a really existing category created separately by the creator. He considered species to be variants of genera that developed from an initial ancestor. Thus, at the lower levels, K. Linnaeus recognized the existence of an evolutionary process, which remains unnoticed at the present time by some authors of textbooks and popular science publications.

The significance of the works of K. Linnaeus is enormous: He legalized the binary nomenclature, introduced standard descriptions of species, proposed a system of taxonomic units: species, genus, family, class, order. And most importantly, he created systems of plants and animals, in their scientific validity, surpassing all systems existing before him. They are called artificial, because of the small number of used characters, but it was the systems of K. Linnaeus that made it possible to talk about the diversity of species and their similarities. The simplicity of the systems attracted many researchers to biology, gave impetus to the description of new species, and brought biology to a new stage of development. Biology began to explain living things, but not only describe them.

J. B. Lamarck's theory of evolution.

In 1809, the French biologist JB Lamarck published the book "Philosophy of Zoology", which outlines the mechanism of the evolution of the organic world. Lamarck's evolutionary theory was based on two laws, which are known as the law of exercise and non-exercise of organs and the law of inheritance of acquired traits. In Lamarck, these laws sound like this. First law. “In every animal that has not reached the limit of its development, a more frequent and unremitting use of an organ strengthens this organ, develops it, increases and imparts strength to it, in proportion to the duration of the use itself, while constant non-use of the organ imperceptibly weakens it, leads to decay, successively diminishes his ability and finally causes his disappearance. " Second law. "Everything that nature has forced to acquire or lose, it retains by reproducing on other individuals." Thus, the essence of Lamarck's theory is that under the influence of the environment, organisms experience changes that are inherited. Since changes are individual in nature, the process of evolution leads to a variety of organisms. A classic example of Lamarck's evolutionary mechanism is the appearance of a giraffe's long neck. For many generations of his short-necked ancestors, they ate the leaves of trees, for which they had to reach higher and higher. The slight lengthening of the neck, which occurred in each generation, was passed on to the next generation, until this part of the body reached its present length.

Lamarck's theory played a significant role in the formation of Charles Darwin's views. In fact, Darwin took the link "environment - variability - heredity" from Lamarck. Lamarck found the reason for the variability. This is due to the environment. He tried to combine the transmission of changes to posterity, that is, the mechanisms of heredity. His theory of "germplasm continuity" existed until the late 19th century.

Despite its enormous significance and simplicity of perception, Lamarck's theory of evolution has not received widespread acceptance. What is the reason for this. Lamarck suggested that the person descended from some four-armed. For this he was pushed by Napoleon, who ordered the destruction of his book. Lamarck denied the real existence of the species, which turned against himself the admirers of Linnaeus, to whom most of the biologists of the early 19th century belonged. And finally, his main methodological mistake: "all acquired traits are inherited." Verification of this position did not give 100% confirmation, and hence the whole theory was questioned. And yet, the significance of the theory of Zh.B. Lamarck is huge. It was he who coined the term - "factors of evolution". And these factors had a material basis.

The undoubted imprint on Charles Darwin's worldview was made by the works of J. Cuvier on fossil remains and C. Lyell, who demonstrated progressive changes in fossil remains.

Traveling around the world on the "Bill" ship, Charles Darwin himself was able to see and appreciate the diversity of plants and animals living on different continents in different conditions. And living in England - a country with a well-developed agriculture, a country that brought everything that was in the world to the island, Charles Darwin could see the results of the "evolutionary" human activity.

And, of course, the most important prerequisite for the emergence of the evolutionary theory of Charles Darwin was Charles Darwin himself, whose genius was able to grasp, analyze all the vast material and create a theory that laid the foundations of Darwinism - the doctrine of the evolution of living organisms.

The main provisions of the evolutionary theory of Charles Darwin.

The theory of evolution by natural selection was formulated by Charles Darwin in 1839. The evolutionary views of Charles Darwin are set forth in full in the book "The Origin of Species by Natural Selection, or the Preservation of Favored Breeds in the Struggle for Life."

The very title of the book suggests that Darwin did not set himself the goal of proving the existence of evolution, the existence of which Confucius had pointed out. When the book was being written, no one doubted the existence of evolution. The main merit of Charles Darwin lies in the fact that he explained how evolution can occur.

The Beagle voyage allowed Darwin to collect a wealth of data on the variability of organisms, which convinced him that species cannot be considered invariable. Returning to England, Charles Darwin took up the practice of breeding pigeons and other domestic animals, which led him to the concept of artificial selection as a method of breeding domestic animals and varieties of cultivated plants. Selecting the deviations he needed, man, bringing these deviations to the necessary requirements, created the necessary breeds and varieties for him.

According to Charles Darwin, the driving forces of this process were hereditary variability and human selection.

However, Charles Darwin had to solve the problem of the action of selection in natural conditions. Charles Darwin's selection mechanism was pushed by the ideas set forth in 1778 by T, Malthus in his work "A Treatise on Population." Malthus vividly described the situation in which population growth could lead if it were not restrained by anything. Darwin transferred Malthus's reasoning to other organisms and drew attention to such factors: despite the high reproductive potential, the population size remains constant. Comparing a huge amount of information, he came to the conclusion that in conditions of fierce competition between members of the population, any changes that are favorable under these conditions would increase the ability of an individual to reproduce and leave behind fertile offspring, and unfavorable changes are obviously unprofitable, and for those who have them organisms, the chances of successful reproduction are reduced. All this served as the basis for determining the driving forces (facts0 of evolution, which, according to Darwin, are variability, heredity, the struggle for existence, natural selection.

In essence, the main meaning of Charles Darwin's evolutionary theory is that evolution occurs on the basis of the appearance of inherited changes, weighing them by the struggle for existence and selection of changes that allow organisms to win in an intense competitive struggle. The result of evolution according to Charles Darwin is the emergence of new species, which leads to a variety of flora and fauna.

Moving forces (factors) of evolution.

The moving forces in evolution are: heredity, variability, the struggle for existence, natural selection.

Heredity.

Heredity is the property of all living organisms to preserve and transmit traits and properties from ancestors to offspring. At the time of Charles Darwin, the nature of this phenomenon was not known. Darwin, as well, assumed the presence of hereditary factors. Criticism of these statements from opponents forced Darwin to abandon his views on the location of the factors, but the very idea of \u200b\u200bthe presence of material factors of heredity permeates all of his teachings. The essence of the phenomenon became clear after T. Morgan developed the chromosome theory. When the structure of the gene was deciphered and understood, the mechanism of heredity became completely clear. It is based on the following factors: the characteristics of the organism (phenotype) are determined by the genotype and environment (reaction rate); the characteristics of an organism are determined by a set of proteins that are formed from polypeptide chains synthesized on ribosomes, information about the structure of the synthesized polypeptide chain is contained on i-RNA, and i-RNA receives this information during the period of template synthesis on the DNA region that is the genome; genes are passed from parents to children and are the material basis of heredity. In interkinesis, DNA duplication occurs, and hence the gene duplication. During the formation of germ cells, the number of chromosomes is reduced, and during fertilization, female and male chromosomes are combined in the zygote. The formation of the embryo and organism occurs under the influence of genes of both the maternal and paternal organism. Inheritance of traits occurs in accordance with the laws of heredity of G. Mendel or on the principle of the intermediate nature of inheritance of traits. In this case, both discrete and mutated genes are inherited.

Thus, heredity itself acts on the one hand as a factor preserving already established characteristics, on the other hand, it ensures the entry of new elements into the structure of the organism.

Variability.

Variability is a universal property of organisms in the process of ontogenesis to acquire new characteristics. C. Darwin noted that there are no two identical individuals in one litter, there are no two identical plants grown from parental seeds. The concept of the forms of variability was developed by Charles Darwin on the basis of studying the breeds of domestic animals. According to Charles Darwin, there are the following forms of variability: definite, indefinite, correlative, hereditary, non-hereditary.

A certain variability is associated with the occurrence in a large number of individuals or in all individuals of a given species, variety or breed during ontogeny. Darwinian mass variability can be associated with specific environmental conditions. A well-chosen diet will increase milk yield in all members of the herd. The combination of favorable conditions promotes an increase in the size of caryopses in all wheat individuals. Thus, changes arising from a certain variability can be predicted.

Uncertain variability is associated with the appearance of traits in individual or several individuals. Such changes cannot be explained by the action of environmental factors.

Relative variability is a very interesting phenomenon. The appearance of some signs leads to the appearance of others. Thus, an increase in the length of the ear of cereals leads to a decrease in the length of the stem. Thus, getting a good harvest, we lose straw. An enlarged limb in insects leads to muscle enlargement. And there are many such examples.

Ch. Darwin noted that some changes occurring in ontogeny are manifested in offspring, others are not manifested. He attributed the former to hereditary variability, the latter to non-hereditary variation. Darwin also noted the fact that it is mainly the changes associated with uncertain and relative variability that are inherited.

An example of a certain variability Darwin considered the action of the environment. Darwin could not have caused the indefinite variability, hence the very name of this form of variability.

By now, the reasons and mechanism of variability are more or less clear.

Modern science distinguishes between two forms of variability - mutational or genotypic and codification or phenotypic.

Mutational variability is associated with a change in the genotype. It arises as a result of mutations. Mutations are the result of the effect on the genotype of mutagens. Themselves mutagens are subdivided into physical, chemical, etc. Mutations are gene, chromosomal, genomic. Mutations are inherited with the genotype.

Modification variability is the interaction of the genotype and the environment. Modification variability is manifested through the reaction rate, i.e., the influence of environmental factors can change the manifestation of a trait in its extreme limits determined by the genotype. Such changes are not transmitted to descendants, but can manifest themselves in the next generation and in the repetition of the parameters of environmental factors.

Usually, Darwinian indefinite variability is associated with mutational, and definite with modification.

Struggle for existence.

At the heart of Darwin's theory of natural selection is the struggle for existence, which inevitably follows from the boundless desire of organisms to reproduce. This desire is always expressed in geometric progressions.

Darwin refers to Malthus. However, long before Malthus, biologists knew about this phenomenon. Yes, and the observations of Darwin himself confirmed the ability of living things to the potential intensity of reproduction. K. Linnaeus also pointed out that a fly fly, through its offspring, could have a horse's carcass a few days before the bones.

Even slowly breeding elephants, according to Charles Darwin's calculations, would take possession of the entire land if there were all the conditions for this. According to Darwin, from one pair of elephants in 740 years, about 19 million individuals would turn out.

Why do potential and real fertility differ so much?

Darwin answers this question too. He writes that the real significance of the abundance of eggs or seeds is to cover their significant loss caused by extermination in any generation of life, that is, reproduction encounters environmental resistance. On the basis of the analysis of this phenomenon, Charles Darwin introduces the concept of "struggle for existence".

"The concept of struggle for existence" can have meaning and justification only in the Darwinian broad "metaphorical" understanding: "including here the dependence of one creature on another, and also including (more importantly) not only the life of one individual, but also its success in leaving your own offspring. " Darwin writes: “About two animals from a row of lions, In the period of famine, we can quite rightly say that they are fighting with each other for food and life. BUT the plant on the outskirts of the desert is also said to fight for life against drought, although it would be more accurate to say that it depends on moisture. About a plant that annually produces thousands of seeds, of which only one grows on average, it is even more accurate to say that it fights against plants of the same genus and others that already cover the soil ... in all this knowledge ... for the sake of convenience, I resort to the general term struggle for Existence".

The text "The Origin of Species" confirms the variety of forms of struggle for existence, but at the same time shows that in all these forms there is an element of competition or competition.

The intraspecific struggle takes place under conditions of fierce competition, since individuals of the same species require the same conditions of existence. In the first place is the role of the organism itself and its individual characteristics. The importance of his means of protection, his activity, his desire to reproduce are noted.

The struggle for existence at the species level is clearly active, and its intensity increases with increasing population density.

Organisms compete with each other in the fight for food, for the female, for the hunting zone, as well as in the means of protection from the adverse effects of the climate, in the protection of offspring.

Deteriorating feeding conditions, high population density, etc., allow the most competitive ones to survive. An example of intraspecific struggle is the situation in a herd of wild deer. An increase in the number of individuals leads to an increase in population density. The number of males in the population increases. An increase in population density leads to a shortage of food, the emergence of epidemics, the struggle of males for a female, etc. All this leads to the death of individuals and a decrease in the population size. The stronger survive.

Thus, intraspecific struggle contributes to the improvement of the species, the emergence of adaptations to the habitat, to the factors causing this struggle.

Often, the interspecies struggle goes in one direction. A classic example is the relationship between hares and wolves. Two hares run away from the wolf. At one point they scatter and the wolf is left with nothing. Interspecies struggle helps to regulate the size of populations, culling sick or weak organisms.

The fight against the factors of the inorganic environment forces plants to adapt to new conditions of existence, pushes them to increase their fertility. On the other hand, the confinement of a species or population to certain habitat conditions is determined. Individuals of meadow bluegrass growing on the prairies and on the plains have an erect stem, and individuals growing in mountainous conditions have an erect stem. As a result of the struggle for existence, individuals survived in which at the early stages of development the stem is pressed to the ground, that is, it fights against night frosts, the most viable plants in mountainous terrain are also strongly lowered plants.

The doctrine of the struggle for existence confirms that it is this factor that is the driving force behind evolution. It is the struggle, whatever you call it, competition, competition. Forces organisms to acquire new traits that allow them to win.

The factor of the struggle for existence is also taken into account in the practical activity of man. When planting plants of the same species, a certain distance between individuals must be observed. When stocking reservoirs with valuable species of fish, predators and low-value species are removed from it. When issuing licenses for shooting wolves, the number of individuals, etc., is taken into account.

Natural selection.

“Natural selection proceeds not through the choice of the most adapted, but through the extermination of the forms most adapted to the conditions of life” - so writes Charles Darwin in The Origin of Species. Natural selection is based on the following premises: a) individuals of any species as a result of variability, biologically not equal to environmental conditions; some of them are more consistent with environmental conditions, others to a lesser extent; b) individuals of any species struggle with unfavorable environmental factors and compete with each other. In the process of this struggle and competition, "as a rule, through the extermination of the unsatisfactory" - the most adapted forms survive. The experience of the fittest is associated with the processes of divergence, during which, under the continuous influence of natural selection, new intraspecific forms are formed. The latter are becoming more and more isolated and serve as a source for the formation of new species and their progressive development. Natural selection - creates new forms of life, creates an amazing adaptability of living forms, ensures the process of increasing the organization, the diversity of life.

Selection begins at the level where competition between individuals is highest. Let us turn to a classic example, about which Charles Darwin himself wrote. In the birch forest, butterflies with a light color prevail. This suggests that butterflies with light coloration have supplanted butterflies with dark and variegated coloration. This process took place under the influence of natural selection for the best protective coloration. When birch is replaced by rocks with a dark color of the bark in this area, butterflies with a light color begin to disappear - they are eaten by birds. The remaining in an insignificant number of the population with a dark color begins to multiply rapidly. There is a selection of individuals who have a chance to survive and give fertile offspring. In this case, we are talking about intergroup competition, that is, the selection is between the already existing forms.

Individuals are also subject to natural selection. Any minor deviation giving an individual's advantage in the struggle for existence can be picked up by natural selection. This is the creative role of selection. It always acts against the background of a moving material that is constantly changing in the processes of mutation and combination.

Natural selection is the main driving force behind evolution.

Types (forms) of natural selection.

There are two main selections: stabilizing and directional.

Stabilizing selection occurs when phenotypic traits correspond to environmental conditions as closely as possible and competition is rather weak. Such selection operates in the entire population, destroying individuals with extreme deviations. For example, there is a certain optimal wing length for a dragonfly of a certain size with a certain lifestyle in a given environment. Stabilizing selection works due to differential reproduction, will destroy those dragonflies whose wingspan is greater or less than optimal. Stabilizing selection does not promote evolutionary change, but maintains the phenotypic stability of a population from generation to generation.

Directed (driving) selection. This form of selection arises in response to a gradual change in environmental conditions. Directional selection affects the range of phenotypes that exist in a given population, and exerts selective pressure that shifts the average phenotype in one direction or another. After the new phenotype comes into optimal correspondence with the new environmental conditions, stabilizing selection comes into play.

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General biology.

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