This handbook contains all the theoretical material on the course of biology necessary for passing the exam. It includes all the elements of the content, verified by control and measuring materials, and helps to generalize and systematize knowledge and skills for the course of secondary (full) school. The theoretical material is presented in a concise, accessible form. Each section is accompanied by examples test items, allowing you to test your knowledge and degree of preparedness for the certification exam. Practical assignments correspond to the USE format. At the end of the manual, there are answers to tests that will help schoolchildren and applicants test themselves and fill in the gaps. The manual is addressed to schoolchildren, applicants and teachers.
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The given introductory fragment of the book Biology. A complete guide to prepare for the exam (G.I. Lerner, 2009) provided by our book partner - Liters company.
The cell as a biological system
2.1. Cell theory, its main provisions, role in the formation of the modern natural science picture of the world. Development of knowledge about the cell. The cellular structure of organisms, the similarity of the structure of cells of all organisms - the basis of the unity of the organic world, evidence of the relationship of living nature
the unity of the organic world, the cell, the cell theory, the provisions of the cell theory.
We have already said that scientific theory is a synthesis of scientific data about the research object. This fully applies to the cell theory created by two German researchers M. Schleiden and T. Schwann in 1839.
The cell theory was based on the work of many researchers who were looking for an elementary structural unit of living things. The creation and development of cell theory was facilitated by the emergence in the 16th century. and further development of microscopy.
Here are the main events that preceded the creation of the cell theory:
- 1590 - creation of the first microscope (the Jansen brothers);
- 1665 Robert Hooke - the first description of the microscopic structure of the cork of an elderberry branch (in fact, these were cell walls, but Hooke introduced the name "cell");
- 1695 Publication of Anthony Levenguk on microbes and other microscopic organisms seen through a microscope;
- 1833 R. Brown described the nucleus of a plant cell;
- 1839 M. Schleiden and T. Schwann discovered the nucleolus.
The main provisions of modern cell theory:
1. All simple and complex organisms consist of cells capable of exchanging substances, energy, biological information with the environment.
2. A cell is an elementary structural, functional and genetic unit of living things.
3. A cell is an elementary unit of reproduction and development of living things.
4. In multicellular organisms, cells are differentiated in structure and function. They are combined into tissues, organs, and organ systems.
5. The cell is an elementary, open living system capable of self-regulation, self-renewal and reproduction.
The cell theory has developed through new discoveries. In 1880, Walter Flemming described chromosomes and the processes that take place in mitosis. Since 1903, genetics began to develop. Beginning in 1930, electron microscopy began to develop rapidly, which allowed scientists to study the finest structure of cellular structures. The 20th century became the century of the flourishing of biology and such sciences as cytology, genetics, embryology, biochemistry, and biophysics. Without the creation of a cell theory, this development would have been impossible.
So, the cell theory states that all living organisms are composed of cells. A cell is that minimal structure of a living thing that has all vital properties - the ability to metabolize, grow, develop, transfer genetic information, self-regulation and self-renewal. The cells of all organisms have similar structural features. However, cells differ from each other in their size, shape and function. An ostrich egg and a frog egg consist of one cell. Muscle cells are contractile, and nerve cells conduct nerve impulses. Differences in the structure of cells largely depend on the functions that they perform in organisms. The more complex the organism is, the more diverse its cells are in their structure and functions. Each type of cell has a specific size and shape. The similarity in the structure of cells of various organisms, the commonality of their basic properties confirm the commonality of their origin and allow us to draw a conclusion about the unity of the organic world.
2.2. A cell is a unit of structure, vital activity, growth and development of organisms. Variety of cells. Comparative characteristics cells of plants, animals, bacteria, fungi
The main bacterial cells, fungal cells, plant cells, animal cells, prokaryotic cells, eukaryotic cells.
The science that studies the structure and function of cells is called cytology ... We have already said that cells can differ from each other in shape, structure and function, although the basic structural elements of most cells are similar. Biologists distinguish two large systematic groups of cells - prokaryotic and eukaryotic ... Prokaryotic cells do not contain a real nucleus and a number of organelles. (See the section "Cell structure".) Eukaryotic cells contain a nucleus, which contains the hereditary apparatus of the body. Prokaryotic cells are cells of bacteria, blue-green algae. The cells of all other organisms are eukaryotic.
Any organism develops from a cell. This applies to organisms that were born as a result of asexual and as a result of sexual reproduction. That is why the cell is considered the unit of growth and development of the organism.
Modern taxonomy distinguishes the following kingdoms of organisms: Bacteria, Fungi, Plants, Animals. The reasons for this division are the ways of feeding these organisms and the structure of cells.
Bacterial cells have the following, characteristic structures for them - a dense cell wall, one circular DNA molecule (nucleotide), ribosomes. These cells lack many of the organelles characteristic of eukaryotic plant, animal, and fungal cells. By the way they eat, bacteria are divided into autotrophs, chemotrophs and heterotrophs... Plant cells contain plastids characteristic only of them - chloroplasts, leukoplasts and chromoplasts; they are surrounded by a dense cellulose cell wall, and also have vacuoles with cell sap. All green plants are autotrophic organisms.
Animal cells do not have dense cell walls. They are surrounded by a cell membrane through which they are metabolized with the environment.
Fungal cells are covered with a cell wall that differs in chemical composition from the cell walls of plants. It contains chitin, polysaccharides, proteins and fats as the main components. The reserve substance of cells of fungi and animals is glycogen.
EXAMPLES OF TASKS
Part A
A1. Which of the following provisions is consistent with the cell theory
1) the cell is an elementary unit of heredity
2) the cell is a unit of reproduction
3) the cells of all organisms are different in their structure
4) the cells of all organisms have a different chemical composition
A2. Precellular life forms include:
1) yeast 3) bacteria
2) penicillus 4) viruses
A3. A plant cell differs from a fungal cell in structure:
1) nucleus 3) cell wall
2) mitochondria 4) ribosomes
A4. One cell consists of:
1) influenza virus and amoeba
2) mushroom mucor and cuckoo flax
3) planarian and volvox
4) green euglena and infusoria-shoe
A5. Prokaryotic cells contain:
1) core 3) Golgi apparatus
2) mitochondria 4) ribosomes
A6. The species of the cell is indicated by:
1) core shape
2) the number of chromosomes
3) membrane structure
4) primary protein structure
A7. The role of cell theory in science is
1) opening the cell nucleus
2) opening the cell
3) generalization of knowledge about the structure of organisms
4) the discovery of metabolic mechanisms
Part B
IN 1. Choose traits that are specific only to plant cells
1) there are mitochondria and ribosomes
2) cellulose cell wall
3) there are chloroplasts
4) storage substance - glycogen
5) reserve substance - starch
6) the core is surrounded by a double membrane
AT 2. Choose the traits that distinguish the kingdom of the Bacteria from the rest of the kingdoms of the organic world.
1) a heterotrophic diet
2) autotrophic diet
3) the presence of a nucleoid
4) lack of mitochondria
5) no core
6) the presence of ribosomes
OT. Find the correspondence between the structural features of the cell and the kingdoms to which these cells belong
Part FROM
C1. Give examples of eukaryotic cells that do not have a nucleus.
C2. Prove that cell theory generalized a number of biological discoveries and predicted new discoveries.
2.3. The chemical organization of the cell. The relationship between the structure and functions of inorganic and organic substances (proteins, nucleic acids, carbohydrates, lipids, ATP) that make up the cell. Justification of the relationship of organisms based on the analysis of the chemical composition of their cells
The main terms and concepts tested in the examination paper: nitrogenous bases, active center of an enzyme, hydrophilicity, hydrophobicity, amino acids, ATP, proteins, biopolymers, denaturation, DNA, deoxyribose, complementarity, lipids, monomer, nucleotide, peptide bond, polymer, carbohydrates, ribose, RNA, enzymes, phospholipids.
2.3.1. Inorganic substances of the cell
The cell contains about 70 elements of the periodic table of elements of Mendeleev, and 24 of them are present in all types of cells. All elements present in the cell are divided, depending on their content in the cell, into groups:
macronutrients - H, O, N, C, Mg, Na, Ca, Fe, K, P, Cl, S;
trace elements - B, Ni, Cu, Co, Zn, Mb, etc .;
ultramicroelements - U, Ra, Au, Pb, Hg, Se, etc.
The cell contains molecules inorganic and organic connections.
Inorganic compounds of the cell - water and inorganic ions.
Water is essential inorganic substance cells. All biochemical reactions take place in aqueous solutions... The water molecule has a nonlinear spatial structure and polarity. Hydrogen bonds are formed between individual water molecules, which determine the physical and chemical properties water.
Physical properties of water: since water molecules are polar, water has the property of dissolving polar molecules of other substances. Substances soluble in water are called hydrophilic... Substances insoluble in water are called hydrophobic.
Water has a high specific heat capacity. To break the numerous hydrogen bonds that exist between water molecules, it takes a lot of energy to be absorbed. Remember how long it takes a kettle to boil. This property of water ensures the maintenance of heat balance in the body.
Enough energy is needed to vaporize water. The boiling point of water is higher than that of many other substances. This property of water protects the body from overheating.
Water can be in three states of aggregation - liquid, solid and gaseous.
Hydrogen bonds determine the viscosity of water and the adhesion of its molecules to the molecules of other substances. Due to the adhesion forces of molecules on the surface of the water, a film is created that has such characteristics as surface tension.
When cooled, the movement of water molecules slows down. The number of hydrogen bonds between molecules becomes maximum. Water reaches its highest density at 4 ° C. When water freezes, it expands (space is needed for the formation of hydrogen bonds) and its density decreases. Therefore, the ice floats.
Biological functions of water... Water ensures the movement of substances in the cell and the body, the absorption of substances and the excretion of metabolic products. In nature, water carries waste products into soils and water bodies.
Water is an active participant in metabolic reactions.
Water is involved in the formation of lubricating fluids and mucus, secretions and juices in the body. These fluids are found in the joints of vertebrates, in the pleural cavity, in the pericardial sac.
Water is part of mucus, which facilitates the movement of substances through the intestines, creates a moist environment on the mucous membranes of the respiratory tract. Secrets secreted by some glands and organs are also water-based: saliva, tears, bile, semen, etc.
Inorganic ions... The inorganic ions of the cell include: cations K +, Na +, Ca 2+, Mg 2+, NH 3 + and anions Cl -, NO 3 -, Н 2 PO 4 -, NCO 3 -, НPO 4 2-.
The difference between the number of cations and anions (Na + , Ka + , Сl -) on the surface and inside the cell provides the emergence of an action potential, which underlies nervous and muscular excitation.
Anions phosphoric acids create phosphate buffer systemmaintaining the pH of the intracellular environment of the body at a level of 6-9.
Carbonic acid and its anions create a bicarbonate buffer system and maintain the pH of the extracellular medium (blood plasma) at 7–4.
Nitrogen compounds serve as a source of mineral nutrition, synthesis of proteins, nucleic acids. Phosphorus atoms are part of nucleic acids, phospholipids, as well as the bones of vertebrates, the chitinous cover of arthropods. Calcium ions are part of the bone substance; they are also necessary for muscle contraction and blood clotting.
EXAMPLES OF TASKS
A1. The polarity of water is due to its ability
1) conduct heat 3) dissolve sodium chloride
2) absorb heat 4) dissolve glycerin
A2. Children with rickets should be given drugs containing
1) iron 2) potassium 3) calcium 4) zinc
A3. Conduction of a nerve impulse is provided by ions:
1) potassium and sodium 3) iron and copper
2) phosphorus and nitrogen 4) oxygen and chlorine
A4. Weak bonds between water molecules in its liquid phase are called:
1) covalent 3) hydrogen
2) hydrophobic 4) hydrophilic
A5. The composition of hemoglobin includes
1) phosphorus 2) iron 3) sulfur 4) magnesium
A6. Select a group chemical elements, necessarily a part of proteins
A7. Patients with hypofunction of the thyroid gland are given drugs containing
Part B
IN 1. Select the functions of water in the cage
1) energy 4) construction
2) enzymatic 5) lubricating
3) transport 6) thermoregulation
AT 2. Select only the physical properties of water
1) the ability to dissociate
2) hydrolysis of salts
3) density
4) thermal conductivity
5) electrical conductivity
6) electron donation
Part FROM
C1. What physical properties of water determine its biological significance?
2.3.2. Organic matter of the cell. Carbohydrates, lipids
Carbohydrates... General formula Cn (H 2 O) n. Therefore, carbohydrates contain only three chemical elements.
Water soluble carbohydrates.
Functions of soluble carbohydrates: transport, protective, signal, energy.
Monosaccharides: glucose - the main source of energy for cellular respiration. Fructose – component flower nectar and fruit juices. Ribose and deoxyribose - structural elements of nucleotides, which are monomers of RNA and DNA.
Disaccharides: sucrose (glucose + fructose) - the main product of photosynthesis, transported in plants. Lactose (glucose + galactose) - part of mammalian milk. Maltose (glucose + glucose) - a source of energy in germinating seeds.
Polymer carbohydrates: starch, glycogen, cellulose, chitin. They are insoluble in water.
Functions of polymeric carbohydrates: structural, storage, energy, protective.
Starch consists of branched spiralized molecules that form storage substances in plant tissues.
Cellulose - a polymer formed by glucose residues, consisting of several straight parallel chains connected by hydrogen bonds. This structure prevents water penetration and ensures the stability of the cellulose shells of plant cells.
Chitin consists of amino derivatives of glucose. The main structural element of the integument of arthropods and the cell walls of fungi.
Glycogen - a reserve substance of an animal cell. Glycogen is even more branchy than starch and is highly soluble in water.
Lipids - esters of fatty acids and glycerin. Insoluble in water, but soluble in non-polar solvents. Present in all cells. Lipids are made up of hydrogen, oxygen and carbon atoms. Types of lipids: fats, waxes, phospholipids. Lipid functions: storing - fats are stored in the tissues of vertebrates. Energy - half of the energy consumed by the cells of vertebrates at rest is formed as a result of fat oxidation. Fats are also used as a source of water. The energy effect from the breakdown of 1 g of fat is 39 kJ, which is twice the energy effect from the breakdown of 1 g of glucose or protein. Protective - the subcutaneous fat layer protects the body from mechanical damage. Structural - phospholipids are part of cell membranes. Heat insulating - subcutaneous fat helps to keep warm. Electrical insulating - myelin secreted by Schwann cells (form sheaths of nerve fibers) isolates some neurons, which speeds up the transmission of nerve impulses many times over. Nutritious - some lipid-like substances help build muscle mass, maintain body tone. Lubricating - waxes cover the skin, wool, feathers and protect them from water. The leaves of many plants are coated with a wax coating; wax is used in the construction of honeycombs. Hormonal - adrenal hormone - cortisone and sex hormones are lipid in nature.
EXAMPLES OF TASK
Part A
A1. The monomer of polysaccharides can be:
1) amino acid
2) glucose
3) nucleotide
4) cellulose
A2. In animal cells, the storage carbohydrate is:
1) cellulose
2) starch
4) glycogen
A3. Most of the energy will be released during splitting:
1) 10 g protein
2) 10 g glucose
3) 10 g fat
4) 10 g amino acid
A4. What function does lipids fail to perform?
1) energy
2) catalytic
3) insulating
4) storage
A5. Lipids can be dissolved in:
2) a solution of table salt
3) hydrochloric acid
4) acetone
Part B
IN 1. Choose the structural features of carbohydrates
1) consist of amino acid residues
2) consist of glucose residues
3) consist of hydrogen, carbon and oxygen atoms
4) some molecules have a branched structure
5) consist of residues of fatty acids and glycerin
6) consist of nucleotides
AT 2. Choose the functions that carbohydrates perform in the body
1) catalytic
2) transport
3) signal
4) construction
5) protective
6) energy
OT. Choose the functions that lipids perform in the cell
1) structural
2) energy
3) storage
4) enzymatic
5) signal
6) transport
AT 4. Relate a group of chemical compounds to their role in the cell
Part FROM
C1. Why doesn't glucose accumulate in the body, but starch and glycogen accumulate?
C2. Why exactly does soap wash away grease from hands?
2.3.3. Proteins, their structure and function
Proteins are biological heteropolymers, the monomers of which are amino acids. Proteins are synthesized in living organisms and perform certain functions in them.
Proteins contain atoms of carbon, oxygen, hydrogen, nitrogen and sometimes sulfur. Monomers of proteins are amino acids - substances that contain unchanged parts of the amino group NH 2 and a carboxyl group COOH and a variable part - a radical. It is by radicals that amino acids differ from each other. Amino acids have the properties of an acid and a base (they are amphoteric), so they can combine with each other. Their number in one molecule can reach several hundred. The alternation of different amino acids in a different sequence makes it possible to obtain a huge number of proteins of different structure and function.
There are 20 types of different amino acids in proteins, some of which animals cannot synthesize. They get them from plants that can synthesize all the amino acids. It is to amino acids that proteins are broken down in the digestive tracts of animals. From these amino acids entering the cells of the body, its new proteins are built.
Protein molecule structure... The structure of a protein molecule is understood as its amino acid composition, the sequence of monomers and the degree of twisting of the molecule, which must fit in various sections and organelles of the cell, and not one, but together with a huge number of other molecules.
The sequence of amino acids in a protein molecule forms its primary structure. It depends on the sequence of nucleotides in the region of the DNA molecule (gene) that encodes a given protein. Neighboring amino acids are linked by peptide bonds between the carbon of the carboxyl group of one amino acid and the nitrogen of the amino group of another amino acid.
The long protein molecule folds up and at first takes the form of a spiral. This is how the secondary structure of the protein molecule arises. Between CO and NH - groups of amino acid residues, adjacent turns of the helix, hydrogen bonds arise that hold the chain.
A protein molecule of complex configuration in the form of a globule (ball) acquires a tertiary structure. The strength of this structure is provided by hydrophobic, hydrogen, ionic and disulfide S-S bonds.
Some proteins have a quaternary structure formed by several polypeptide chains (tertiary structures). The quaternary structure is also held by weak non-covalent bonds - ionic, hydrogen, hydrophobic. However, the strength of these bonds is weak and the structure can be easily broken. When heated or treated with certain chemicals, the protein denatures and loses its biological activity. Violation of the quaternary, tertiary and secondary structures is reversible. The destruction of the primary structure is irreversible.
In any cell, there are hundreds of protein molecules that perform various functions. In addition, proteins are species specific. This means that each type of organism has proteins that are not found in other species. This creates serious difficulties in the transplantation of organs and tissues from one person to another, in the grafting of one plant species on another, etc.
Protein functions.
Catalytic (enzymatic) - proteins accelerate all biochemical processes in the cell: cleavage nutrients in the digestive tract, participate in matrix synthesis reactions. Each enzyme accelerates one and only one reaction (both forward and backward). The rate of enzymatic reactions depends on the temperature of the medium, the level of its pH, as well as on the concentrations of the reactants and the concentration of the enzyme.
Transport - proteins provide active transport of ions across cell membranes, transport of oxygen and carbon dioxide, transport of fatty acids.
Protective - antibodies provide the body's immune defense; fibrinogen and fibrin protect the body from blood loss.
Structural - one of the main functions of proteins. Proteins are part of cell membranes; the protein keratin forms hair and nails; proteins collagen and elastin - cartilage and tendons.
Contractile - provided by contractile proteins - actin and myosin.
Signal - protein molecules can receive signals and serve as their carriers in the body (hormones). Remember that not all hormones are proteins.
Energy - with prolonged fasting, proteins can be used as an additional source of energy after carbohydrates and fats are consumed.
EXAMPLES OF TASKS
Part A
A1. The sequence of amino acids in a protein molecule depends on:
1) gene structure
2) the external environment
3) their random combination
4) their structures
A2. Man gets essential amino acids by
1) their synthesis in cells
2) food intake
3) taking medication
4) taking vitamins
A3. With a decrease in temperature, the activity of enzymes
1) increases markedly
2) decreases markedly
3) remains stable
4) changes periodically
A4. Participates in protecting the body from blood loss
1) hemoglobin
2) collagen
A5. In which of these processes are proteins not involved?
1) metabolism
2) coding of hereditary information
3) enzymatic catalysis
4) transport of substances
A6. Give an example of a peptide bond:
Part B
IN 1. Choose functions specific to proteins
1) catalytic
2) hematopoietic
3) protective
4) transport
5) reflex
6) photosynthetic
AT 2. Establish a correspondence between the structure of a protein molecule and its features
Part FROM
C1. Why is food stored in the refrigerator?
C2. Why do cooked foods last longer?
SZ. Explain the concept of "specificity" of a protein, and what is the biological significance of specificity?
C4. Read the text, indicate the numbers of sentences in which mistakes were made and explain them 1) Most of the chemical reactions in the body are catalyzed by enzymes. 2) Each enzyme can catalyze many types of reactions. 3) The enzyme has an active center, the geometric shape of which changes depending on the substance with which the enzyme interacts. 4) An example of the action of the enzyme can be the decomposition of urea by urease. 5) Urea decomposes into carbon dioxide and ammonia, which smells like a cat's litter box. 6) In one second, urease breaks down up to 30,000 urea molecules, under normal conditions it would take about 3 million years.
2.3.4 Nucleic acids
Nucleic acids were discovered in 1868 by the Swiss scientist F. Mischer. In organisms, there are several types of nucleic acids that are found in various organelles of the cell - the nucleus, mitochondria, and plastids. Nucleic acids include DNA, i-RNA, t-RNA, r-RNA.
Deoxyribonucleic acid (DNA) - a linear polymer in the form of a double helix formed by a pair of antiparallel complementary (corresponding to each other in configuration) chains. The spatial structure of the DNA molecule was modeled by American scientists James Watson and Francis Crick in 1953.
DNA monomers are nucleotides ... Each nucleotide of DNA consists of purine (A - adenine or G - guanine) or pyrimidine (T - thymine or C - cytosine) nitrogenous base, five-carbon sugar - deoxyribose and phosphate group.
Nucleotides in a DNA molecule are facing each other with nitrogenous bases and are combined in pairs in accordance with the rules of complementarity: thymine is located opposite adenine, cytosine is opposite guanine. The A - T pair is linked by two hydrogen bonds, and the G - C pair - by three. During replication (doubling) of a DNA molecule, hydrogen bonds are broken and the chains diverge, and a new DNA chain is synthesized on each of them. The backbone of DNA chains is formed by sugar phosphate residues.
The sequence of nucleotides in a DNA molecule determines its specificity, as well as the specificity of the body proteins encoded by this sequence. These sequences are individual for each type of organism, and for individual individuals.
Example: the DNA nucleotide sequence is given: CHA - TTA - CAA.
The messenger RNA (m-RNA) will be used to synthesize the HCC - AAU - GUU chain, as a result of which a chain of amino acids will be built: alanine - asparagine - valine.
When replacing nucleotides in one of the triplets or rearranging them, this triplet will encode another amino acid, and therefore the protein encoded by this gene will also change. (Taking advantage of school textbook, try to verify this.) Changes in the composition of nucleotides or their sequence are called mutations.
Ribonucleic acid (RNA) - a linear polymer consisting of one nucleotide chain. In the RNA, the thymine nucleotide is substituted for the uracil (U) nucleotide. Each RNA nucleotide contains a five-carbon sugar - ribose, one of four nitrogenous bases and a phosphoric acid residue.
Types of RNA. Matrix, or informational, RNA. It is synthesized in the nucleus with the participation of the RNA polymerase enzyme. It is complementary to the DNA site where the synthesis takes place. Its function is to remove information from DNA and transfer it to the site of protein synthesis - to ribosomes. Makes 5% of the RNA of the cell. Ribosomal RNA - is synthesized in the nucleolus and is part of the ribosomes. It makes up 85% of the cell RNA. Transport RNA (more than 40 types). It transports amino acids to the site of protein synthesis. It is shaped like a clover leaf and consists of 70–90 nucleotides.
Adenosine triphosphoric acid - ATP... ATP is a nucleotide consisting of a nitrogenous base - adenine, a carbohydrate ribose and three phosphoric acid residues, two of which store a large amount of energy. When one residue of phosphoric acid is cleaved off, 40 kJ / mol of energy is released. Compare this figure with the figure for the energy released per gram of glucose or fat. The ability to store this amount of energy makes ATP a universal source of energy. ATP synthesis occurs mainly in the mitochondria.
EXAMPLES OF TASKS
Part A
A1. DNA and RNA monomers are
1) nitrogenous bases
2) phosphate groups
3) amino acids
4) nucleotides
A2. Messenger RNA function:
1) doubling information
2) removing information from DNA
3) transport of amino acids to ribosomes
4) information storage
A3. Indicate the second DNA strand, complementary to the first: ATT - HCC - TSH
1) UAA - TGG - AAC
2) TAA - CHG - AAC
3) UCC - HCC - ACG
4) TAA - UGG - UUC
A4. The hypothesis that DNA is the genetic material of a cell is confirmed by:
1) the number of nucleotides in the molecule
2) DNA personality
3) the ratio of nitrogenous bases (A \u003d T, G \u003d C)
4) the ratio of DNA in gametes and somatic cells (1: 2)
A5. The DNA molecule is capable of transmitting information due to:
1) nucleotide sequences
2) the number of nucleotides
3) the ability to self-duplicate
4) spiralization of the molecule
A6. When is the composition of one of the RNA nucleotides indicated correctly?
1) thymine - ribose - phosphate
2) uracil - deoxyribose - phosphate
3) uracil - ribose - phosphate
4) adenine - deoxyribose - phosphate
Part B
IN 1. Select the signs of a DNA molecule
1) Single-stranded molecule
2) Nucleotides - ATUC
3) Nucleotides - ATGC
4) Carbohydrate - ribose
5) Carbohydrate - deoxyribose
6) Capable of replication
AT 2. Select functions specific to eukaryotic cell RNA molecules
1) distribution of hereditary information
2) transmission of hereditary information to the site of protein synthesis
3) transport of amino acids to the site of protein synthesis
4) initiation of DNA replication
5) the formation of the structure of ribosomes
6) storage of hereditary information
Part FROM
C1. Establishing the structure of DNA made it possible to solve a number of problems. What problems do you think these were and how were they resolved as a result of this discovery?
C2. Compare nucleic acids for composition and properties.
2.4. The structure of pro- and eukaryotic cells. The relationship between the structure and functions of parts and organelles of a cell is the basis of its integrity
The main terms and concepts tested in the examination paper: golgi apparatus, vacuole, cell membrane, cell theory, leukoplasts, mitochondria, cell organelles, plastids, prokaryotes, ribosomes, chloroplasts, chromoplasts, chromosomes, eukaryotes, nucleus.
Any cell is a system. This means that all of its components are interconnected, interdependent and interact with each other. This also means that disruption of one of the elements of a given system leads to changes and disruptions in the operation of the entire system. The set of cells forms tissues, various tissues form organs, and organs, interacting and performing common function, form organ systems. This chain can be continued further, and you can do it yourself. The main thing to understand is that any system has a certain structure, level of complexity and is based on the interaction of the elements that make it up. Below are reference tables that compare the structure and function of prokaryotic and eukaryotic cells, as well as their structure and function. Carefully analyze these tables, because in the examination papers, questions are often asked that require knowledge of this material.
2.4.1. Features of the structure of eukaryotic and prokaryotic cells. Comparative data
Comparative characteristics of eukaryotic and prokaryotic cells.
The structure of eukaryotic cells.
Functions of eukaryotic cells ... The cells of unicellular organisms perform all the functions characteristic of living organisms - metabolism, growth, development, reproduction; adaptable.
The cells of multicellular organisms are differentiated in structure, depending on the functions they perform. Epithelial, muscle, nerve, connective tissues are formed from specialized cells.
EXAMPLES OF TASKS
Part A
A1. Prokaryotic organisms include
1) bacillus
4) Volvox
A2. The cell membrane performs the function
1) protein synthesis
2) transfer of hereditary information
3) photosynthesis
4) phagocytosis and pinocytosis
A3. Indicate the point at which the structure of the named cell coincides with its function
1) neuron - contraction
2) leukocyte - impulse conduction
3) erythrocyte - transport of gases
4) osteocyte - phagocytosis
A4. Cellular energy is produced in
1) ribosomes
2) mitochondria
4) the Golgi apparatus
A5. Exclude an unnecessary concept from the proposed list
1) lamblia
2) plasmodium
3) ciliates
4) chlamydomonas
A6. Exclude an unnecessary concept from the proposed list
1) ribosomes
2) mitochondria
3) chloroplasts
4) starch grains
A7. The chromosomes of the cell perform the function
1) protein biosynthesis
2) storage of hereditary information
3) the formation of lysosomes
4) regulation of metabolism
Part B
IN 1. Choose from the list of functions of chloroplasts
1) the formation of lysosomes
2) glucose synthesis
3) RNA synthesis
5) oxygen evolution
6) cellular respiration
AT 2. Select the structural features of mitochondria
1) surrounded by a double membrane
3) there are cristae
4) the outer membrane is folded
5) surrounded by a single membrane
6) the inner membrane is rich in enzymes
OT. Relate the organoid to its function
AT 4. Fill in the table, marking with signs "+" or "-" the presence of these structures in pro- and eukaryotic cells
Part FROM
C1. Prove that the cell is a complete biological, open system.
2.5. Metabolism: energy and plastic metabolism, their relationship. Enzymes, their chemical nature, role in metabolism. Stages of energy metabolism. Fermentation and breathing. Photosynthesis, its significance, cosmic role. Phases of photosynthesis. Light and dark reactions of photosynthesis, their relationship. Chemosynthesis. The role of chemosynthetic bacteria on Earth
Terms tested in the examination paper: autotrophic organisms, anabolism, anaerobic glycolysis, assimilation, aerobic glycolysis, biological oxidation, fermentation, dissimilation, biosynthesis, heterotrophic organisms, respiration, catabolism, oxygen stage, metabolism, plastic metabolism, preparatory stage, light phase of photosynthesis, dark phase of photosynthesis, water photolysis , photosynthesis, energy metabolism.
2.5.1. Energy and plastic metabolism, their relationship
Metabolism (metabolism) Is a set of interrelated processes of synthesis and breakdown of chemicals that take place in the body. Biologists divide it into plastic ( anabolism) and energy exchanges ( catabolism) that are related. All synthetic processes require substances and energy supplied by cleavage processes. Cleavage processes are catalyzed by enzymes synthesized during plastic metabolism, using the products and energy of energy metabolism.
For certain processes occurring in organisms, the following terms are used:
Anabolism (assimilation) - synthesis of more complex monomers from simpler ones with absorption and accumulation of energy in the form of chemical bonds in synthesized substances.
Catabolism (dissimilation) - the decomposition of more complex monomers into simpler ones with the release of energy and its storage in the form of high-energy ATP bonds.
Living beings use light and chemical energy for their life. Green plants - autotrophs , - synthesize organic compounds in the process of photosynthesis, using the energy of sunlight. The source of carbon for them is carbon dioxide. Many autotrophic prokaryotes produce energy in the process chemosynthesis - oxidation of inorganic compounds. For them, the source of energy can be compounds of sulfur, nitrogen, carbon. Heterotrophs use organic carbon sources, that is, they feed on ready-made organic substances. Among the plants, there may be those that feed in a mixed way ( mixotrophic) - sundew, venus flytrap, or even heterotrophic - rafflesia. Of the representatives of unicellular animals, green euglena are considered mixotrophs.
Enzymes, their chemical nature, role in metabolism... Enzymes are always specific proteins - catalysts. The term "specific" means that the object in relation to which this term is used has unique features, properties, characteristics. Each enzyme has such characteristics, because, as a rule, it catalyzes a certain type of reaction. Not a single biochemical reaction in the body occurs without the participation of enzymes. The specific features of the enzyme molecule are explained by its structure and properties. The enzyme molecule contains an active center, the spatial configuration of which corresponds to the spatial configuration of the substances with which the enzyme interacts. Having recognized its substrate, the enzyme interacts with it and accelerates its transformation.
All biochemical reactions are catalyzed by enzymes. Without their participation, the speed of these reactions would decrease hundreds of thousands of times. Examples include such reactions as the participation of RNA - polymerase in the synthesis of - m-RNA on DNA, the effect of urease on urea, the role of ATP - synthetase in the synthesis of ATP, and others. Note that many enzymes end in aza.
The activity of enzymes depends on temperature, acidity of the environment, and the amount of substrate with which it interacts. As the temperature rises, enzyme activity increases. However, this happens up to certain limits, since at sufficiently high temperatures the protein is denatured. The environment in which enzymes can function is different for each group. There are enzymes that are active in an acidic or slightly acidic environment or in an alkaline or slightly alkaline environment. In an acidic environment, enzymes of gastric juice are active in mammals. In a weakly alkaline environment, intestinal juice enzymes are active. The digestive enzyme of the pancreas is active in an alkaline environment. Most enzymes are active in a neutral environment.
2.5.2. Energy metabolism in the cell (dissimilation)
Energy exchange Is a set of chemical reactions of gradual decomposition of organic compounds, accompanied by the release of energy, part of which is spent on the synthesis of ATP. Degradation of organic compounds in aerobic organisms occur in three stages, each of which is accompanied by several enzymatic reactions.
First step - preparatory ... In the gastrointestinal tract of multicellular organisms, it is carried out by digestive enzymes. In unicellular organisms - by lysosome enzymes. At the first stage, proteins are broken down to amino acids, fats to glycerol and fatty acids, polysaccharides to monosaccharides, nucleic acids to nucleotides. This process is called digestion.
Second phase - anoxic (glycolysis ). Its biological meaning lies in the beginning of the gradual breakdown and oxidation of glucose with the accumulation of energy in the form of 2 ATP molecules. Glycolysis occurs in the cytoplasm of cells. It consists of several successive reactions of the conversion of a glucose molecule into two molecules of pyruvic acid (pyruvate) and two ATP molecules, in the form of which a part of the energy released during glycolysis is stored: C 6 H 12 O 6 + 2ADP + 2F → 2C 3 H 4 O 3 + 2ATF. The rest of the energy is dissipated as heat.
In yeast and plant cells ( with a lack of oxygen) pyruvate decomposes into ethanol and carbon dioxide. This process is called alcoholic fermentation .
The energy accumulated during glycolysis is too little for organisms that use oxygen to breathe. That is why lactic acid (C 3 H 6 O 3) is formed in the muscles of animals, including humans, under heavy loads and a lack of oxygen, which accumulates in the form of lactate. Muscle pain appears. In untrained people it happens faster than in trained people.
The third stage is oxygen , consisting of two sequential processes - the Krebs cycle, named after the Nobel laureate Hans Krebs, and oxidative phosphorylation. Its meaning lies in the fact that during oxygen respiration, pyruvate is oxidized to the final products - carbon dioxide and water, and the energy released during oxidation is stored in the form of 36 ATP molecules. (34 molecules in the Krebs cycle and 2 molecules in the course of oxidative phosphorylation). This energy of decomposition of organic compounds provides the reactions of their synthesis in plastic exchange. The oxygen stage arose after the accumulation of a sufficient amount of molecular oxygen in the atmosphere and the appearance of aerobic organisms.
Oxidative phosphorylation or cellular respiration occurs on the inner membranes of mitochondria, in which electron carrier molecules are embedded. During this stage, most of the metabolic energy is released. Carrier molecules transport electrons to molecular oxygen. Part of the energy is dissipated in the form of heat, and part is spent on the formation of ATP.
The total reaction of energy metabolism:
C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O + 38ATP.
EXAMPLES OF TASKS
A1. The way of feeding predatory animals is called
1) autotrophic
2) mixotrophic
3) heterotrophic
4) chemotrophic
A2. The set of metabolic reactions is called:
1) anabolism
2) assimilation
3) dissimilation
4) metabolism
A3. On preparatory stage energy metabolism is formed:
1) 2 molecules of ATP and glucose
2) 36 molecules of ATP and lactic acid
3) amino acids, glucose, fatty acids
4) acetic acid and alcohol
A4. Substances that catalyze biochemical reactions in the body are:
2) nucleic acids
4) carbohydrates
A5. The process of ATP synthesis during oxidative phosphorylation occurs in:
1) cytoplasm
2) ribosomes
3) mitochondria
4) the Golgi apparatus
A6. The energy of ATP stored in the process of energy metabolism is partially used for the reactions:
1) preparatory stage
2) glycolysis
3) oxygen stage
4) synthesis of organic compounds
A7. Glycolysis products are:
1) glucose and ATP
2) carbon dioxide and water
3) pyruvic acid and ATP
4) proteins, fats, carbohydrates
Part B
IN 1. Select the events that occur at the preparatory stage of energy metabolism in a person
1) proteins break down to amino acids
2) glucose is broken down to carbon dioxide and water
3) 2 ATP molecules are synthesized
4) glycogen is broken down to glucose
5) lactic acid is formed
6) lipids are broken down to glycerol and fatty acids
AT 2. Correlate the processes occurring during energy exchange with the stages at which they occur
OT. Determine the sequence of transformations of a piece of raw potato in the process of energy metabolism in the pig's body:
A) the formation of pyruvate
B) the formation of glucose
C) absorption of glucose into the blood
D) the formation of carbon dioxide and water
E) oxidative phosphorylation and the formation of H 2 O
E) the Krebs cycle and the formation of CO 2
Part C
C1. Explain the causes of fatigue in marathon athletes at distances, and how is it overcome?
2.5.3. Photosynthesis and chemosynthesis
All living things need food and nutrients. Eating, they use energy stored primarily in organic compounds - proteins, fats, carbohydrates. Heterotrophic organisms, as already mentioned, use food of plant and animal origin that already contains organic compounds. Plants create organic matter through photosynthesis. Research in the field of photosynthesis began in 1630 with the experiments of the Dutchman van Helmont. He proved that plants receive organic matter not from the soil, but create them on their own. Joseph Priestley in 1771 proved the "correction" of air with plants. Placed under a glass cover, they absorbed carbon dioxide emitted by a smoldering torch. Research has continued and it has now been found that photosynthesis Is a process of the formation of organic compounds from carbon dioxide (CO 2) and water using the energy of light and takes place in the chloroplasts of green plants and the green pigments of some photosynthetic bacteria.
Chloroplasts and folds of the cytoplasmic membrane of prokaryotes contain a green pigment - chlorophyll... The chlorophyll molecule is able to be excited by sunlight and donate its electrons and move them to higher energy levels. This process can be compared to a ball tossed up. As it rises, the ball stores up potential energy; falling, he loses her. Electrons do not fall back, but are picked up by electron carriers (NADP + - nicotinamide diphosphate). In this case, the energy accumulated earlier by them is partially spent on the formation of ATP. Continuing the comparison with a tossed ball, we can say that the ball, falling, heats the surrounding space, and part of the energy of the falling electrons is stored in the form of ATP. The process of photosynthesis is divided into reactions caused by light and reactions associated with carbon fixation. They are called light and dark phases.
"Light phase" - This is the stage at which the light energy absorbed by chlorophyll is converted into electrochemical energy in the electron transport chain. It is carried out in the light, in gran membranes with the participation of carrier proteins and ATP synthetase.
Light-induced reactions occur on the photosynthetic membranes of the granular chloroplasts:
1) excitation of chlorophyll electrons by light quanta and their transition to a higher energy level;
2) restoration of electron acceptors - NADP + to NADP H
2H + + 4e - + NADP + → NADPH;
3) photolysis of waterwhich occurs with the participation of light quanta: 2H 2 O → 4H + + 4e - + O 2.
This process takes place inside thylakoids - folds of the inner membrane of chloroplasts. Granas are formed from thylakoids - stacks of membranes.
Since the examination papers ask not about the mechanisms of photosynthesis, but about the results of this process, then we will move on to them.
The results of light reactions are: photolysis of water with the formation of free oxygen, synthesis of ATP, reduction of NADP + to NADP H. Thus, light is needed only for the synthesis of ATP and NADP-H.
"Dark phase" - the process of converting CO 2 into glucose in the stroma (space between the grains) of chloroplasts using the energy of ATP and NADP H.
The result of dark reactions is the conversion of carbon dioxide to glucose and then to starch. In addition to glucose molecules in the stroma, the formation of amino acids, nucleotides, and alcohols occurs.
The total equation of photosynthesis is
The importance of photosynthesis... In the process of photosynthesis, free oxygen is formed, which is necessary for the respiration of organisms:
oxygen forms a protective ozone screen, which protects organisms from the harmful effects of ultraviolet radiation;
photosynthesis provides the production of original organic substances, and therefore food for all living things;
photosynthesis helps to reduce the concentration of carbon dioxide in the atmosphere.
Chemosynthesis - the formation of organic compounds from inorganic ones due to the energy of redox reactions of nitrogen, iron, sulfur compounds. There are several types of chemosynthetic reactions:
1) oxidation of ammonia to nitrous and nitric acid by nitrifying bacteria:
NH 3 → HNQ 2 → HNO 3 + Q;
2) the transformation of ferrous iron into ferric iron bacteria:
Fe 2+ → Fe 3+ + Q;
3) oxidation of hydrogen sulfide to sulfur or sulfuric acid by sulfur bacteria
H 2 S + O 2 \u003d 2H 2 O + 2S + Q,
H 2 S + O 2 \u003d 2H 2 SO 4 + Q.
The released energy is used for the synthesis of organic substances.
The role of chemosynthesis. Bacteria - chemosynthetics, destroy rocks, purify waste water, participate in the formation of minerals.
EXAMPLES OF TASKS
A1. Photosynthesis is a process that takes place in green plants. It is associated with:
1) decomposition of organic substances to inorganic
2) the creation of organic substances from inorganic
3) the chemical conversion of glucose into starch
4) the formation of cellulose
A2. The starting material for photosynthesis is
1) proteins and carbohydrates
2) carbon dioxide and water
3) oxygen and ATP
4) glucose and oxygen
A3. The light phase of photosynthesis occurs
1) in chloroplast granules
2) in leukoplasts
3) in the stroma of chloroplasts
4) in mitochondria
A4. The energy of excited electrons in the light stage is used for:
1) ATP synthesis
2) glucose synthesis
3) protein synthesis
4) breakdown of carbohydrates
A5. As a result of photosynthesis in chloroplasts, the following are formed:
1) carbon dioxide and oxygen
2) glucose, ATP and oxygen
3) proteins, fats, carbohydrates
4) carbon dioxide, ATP and water
A6. Chemotrophic organisms include
1) causative agents of tuberculosis
2) lactic acid bacteria
3) sulfur bacteria
Part B
IN 1. Select the processes occurring in the light phase of photosynthesis
1) photolysis of water
2) the formation of glucose
3) synthesis of ATP and NADP H
4) use of СО 2
5) the formation of free oxygen
6) use of energy ATP
AT 2. Select substances involved in photosynthesis
1) cellulose
2) glycogen
3) chlorophyll
4) carbon dioxide
6) nucleic acids
Part FROM
C1. What conditions are necessary to start the process of photosynthesis?
C2. How does the structure of a leaf ensure its photosynthetic functions?
2.6. Biosynthesis of protein and nucleic acids. Matrix character of biosynthesis reactions. Genetic information in the cell. Genes, genetic code and its properties
Terms and concepts tested in the examination paper: anticodon, biosynthesis, gene, genetic information, genetic code, codon, matrix synthesis, polysome, transcription, translation.
Genes, genetic code and its properties... More than 6 billion people already live on Earth. Except for 25-30 million pairs of identical twins, then genetically all people are different. This means that each of them is unique, has unique hereditary characteristics, character traits, abilities, temperament and many other qualities. What determines such differences between people? Of course, the differences in their genotypes, that is, the sets of genes of a given organism. Each person is unique, just as the genotype of an individual animal or plant is unique. But the genetic traits of a given person are embodied in proteins synthesized in his body. Consequently, the structure of the protein of one person differs, albeit quite slightly, from the protein of another person. That is why the problem of organ transplantation arises, that is why there are allergic reactions to food, insect bites, plant pollen, etc. This does not mean that people do not have exactly the same proteins. Proteins that perform the same functions may be the same or only slightly differ by one or two amino acids from each other. But there are no people on Earth (with the exception of identical twins) in whom all proteins would be the same.
Information about the primary structure of a protein is encoded in the form of a sequence of nucleotides in a section of a DNA molecule - a gene. Gene Is a unit of hereditary information of an organism. Each DNA molecule contains many genes. The totality of all genes of an organism constitutes its genotype.
Hereditary information is encoded using genetic code... The code is similar to the well-known Morse code, which encodes information with dots and dashes. Morse code is universal for all radio operators, and the only differences are in the translation of signals into different languages. Genetic code It is also universal for all organisms and differs only in the alternation of nucleotides that form genes and coding for proteins of specific organisms. So what exactly is the genetic code? Initially, it consists of triplets (triplets) of DNA nucleotides, combined in a different sequence. For example, AAT, HCA, ACG, THC, etc. Each triplet of nucleotides encodes a specific amino acid that will be inserted into the polypeptide chain. For example, the CGT triplet encodes the amino acid alanine, and the AAG triplet encodes the phenylalanine amino acid. There are 20 amino acids, and 64 possibilities for combinations of four nucleotides into groups of three. Therefore, four nucleotides are enough to encode 20 amino acids. This is why one amino acid can be encoded by several triplets. Some of the triplets do not code for amino acids at all, but start or stop protein biosynthesis. The code itself is considered the sequence of nucleotides in an i-RNA molecule, because it removes information from DNA (transcription process) and translates it into a sequence of amino acids in the molecules of synthesized proteins (translation process). The composition and RNA includes the nucleotides of the ACGU. Triplets of m-RNA nucleotides are called codons ... The already cited examples of DNA triplets on m-RNA will look like this - the CGT triplet on m-RNA will become the HCA triplet, and the DNA triplet - AAG - will become the UUC triplet. It is the m-RNA codons that reflect the genetic code in the record. So, the genetic code is triplet, universal for all organisms on earth, degenerated (each amino acid is encrypted with more than one codon). There are punctuation marks between the genes - these are triplets called stop codons. They signal the end of the synthesis of one polypeptide chain. There are tables of the genetic code that you need to be able to use to decipher the m-RNA codons and build chains of protein molecules.
Protein biosynthesis - This is one of the types of plastic metabolism, during which hereditary information encoded in DNA genes is realized in a specific sequence of amino acids in protein molecules. Genetic information taken from DNA and translated into the code of the i-RNA molecule must be realized, that is, manifest in the characteristics of a particular organism. These signs are determined by proteins. Protein biosynthesis occurs on ribosomes in the cytoplasm. This is where the informational RNA comes from the cell nucleus. If the synthesis of i-RNA on a DNA molecule is called transcription, then protein synthesis on ribosomes is called broadcast - translation of the language of the genetic code into the language of the sequence of amino acids in a protein molecule. Amino acids are delivered to the ribosomes by transport RNAs. These RNAs are in the shape of a clover leaf. At the end of the molecule there is a site for the attachment of an amino acid, and at the top there is a triplet of nucleotides, complementary to a certain triplet - a codon on the m-RNA. This triplet is called an anticodon. After all, he deciphers the i-RNA code. There are always the same number of t-RNAs in a cell as there are codons encoding amino acids.
The ribosome moves along the i-RNA, shifting by three nucleotides when a new amino acid approaches, freeing them for a new anticodon. The amino acids delivered to the ribosomes are oriented in relation to each other so that the carboxyl group of one amino acid is adjacent to the amino group of another amino acid. As a result, a peptide bond is formed between them. A polypeptide molecule is gradually formed.
Protein synthesis continues until one of three stop codons appears on the ribosome - UAA, UAH, or UGA.
After this, the polypeptide leaves the ribosome and is sent to the cytoplasm. On one i-RNA molecule there are several ribosomes that form polysome... It is on polysomes that the simultaneous synthesis of several the same polypeptide chains.
Each stage of biosynthesis is catalyzed by a corresponding enzyme and supplied with the energy of ATP.
Biosynthesis occurs in cells at a tremendous rate. In the body of higher animals, up to 60 thousand peptide bonds are formed in one minute.
Matrix synthesis reactions... Matrix synthesis reactions include replication DNA, synthesis of i-RNA on DNA ( transcription), and protein synthesis on i-RNA ( broadcast), as well as the synthesis of RNA or DNA on the RNA of viruses.
DNA replication... The structure of the DNA molecule, established by J. Watson and F. Crick in 1953, met the requirements that were imposed on the molecule-keeper and transmitter of hereditary information. A DNA molecule consists of two complementary strands. These chains are held together by weak hydrogen bonds that can be broken by enzymes.
A molecule is capable of self-doubling (replication), and a new half of it is synthesized on each old half of the molecule. In addition, an i-RNA molecule can be synthesized on a DNA molecule, which then transfers the information received from DNA to the site of protein synthesis. Information transfer and protein synthesis are based on a matrix principle, comparable to the operation of a printing press in a printing house. Information from DNA is copied many times. If errors occur during copying, they will be repeated in all subsequent copies. True, some errors in copying information by a DNA molecule can be corrected. This error recovery process is called reparations... The first of the reactions in the process of transferring information is the replication of the DNA molecule and the synthesis of new DNA strands.
Replication - This is the process of self-duplication of the DNA molecule, carried out under the control of enzymes. On each of the DNA strands formed after the break of hydrogen bonds, with the participation of the DNA polymerase enzyme, a daughter DNA chain is synthesized. The material for synthesis is free nucleotides present in the cytoplasm of cells.
The biological meaning of replication lies in the exact transfer of hereditary information from the parent molecule to the daughter ones, which normally occurs during the division of somatic cells.
Transcription is the process of removing information from a DNA molecule synthesized on it by an i-RNA molecule. Messenger RNA consists of one strand and is synthesized on DNA in accordance with the rule of complementarity. As in any other biochemical reaction, an enzyme is involved in this synthesis. It activates the beginning and end of the synthesis of the i-RNA molecule. The finished i-RNA molecule enters the cytoplasm on the ribosomes, where the synthesis of polypeptide chains occurs. The process of translating information contained in a nucleotide sequence of an m-RNA into an amino acid sequence in a polypeptide is called broadcast .
EXAMPLES OF TASKS
Part A
A1. Which statement is wrong?
1) the genetic code is universal
2) the genetic code is degenerate
3) the genetic code is individual
4) the genetic code is triplet
A2. One DNA triplet encodes:
1) the sequence of amino acids in a protein
2) one sign of an organism
3) one amino acid
4) several amino acids
A3. "Punctuation marks" of the genetic code
1) trigger protein synthesis
2) stop protein synthesis
3) encode certain proteins
4) encode a group of amino acids
A4. If in a frog the amino acid VALIN is encoded by the GUU triplet, then in a dog this amino acid can be encoded by triplets (see table):
1) GUA and GUG 3) CTC and CUA
2) UUC and UCA 4) UAG and UGA
A5. Protein synthesis is completed at the moment
1) recognition of a codon by an anticodon
2) receipt of i-RNA on ribosomes
3) the appearance of a "punctuation mark" on the ribosome
4) attachment of amino acids to t-RNA
A6. Indicate a pair of cells in which one person contains different genetic information?
1) liver and stomach cells
2) neuron and leukocyte
3) muscle and bone cells
4) tongue cell and egg cell
A7. Function of i-RNA in the process of biosynthesis
1) storage of hereditary information
2) transport of amino acids to ribosomes
3) transfer of information to ribosomes
4) acceleration of the biosynthesis process
A8. Anticodon t-RNA consists of UCH nucleotides. What DNA triplet is complementary to it?
Part B
IN 1. Establish a correspondence between the characteristic of the process and its name
Part C
C1. Indicate the sequence of amino acids in a protein molecule encoded by the following codon sequence: UUA - AUU - HCU - GHA
C2. List all the steps in protein biosynthesis.
2.7. A cell is a genetic unit of a living thing. Chromosomes, their structure (shape and size) and functions. The number of chromosomes and their species constancy. Features of somatic and germ cells. Cell life cycle: interphase and mitosis. Mitosis is the division of somatic cells. Meiosis. Phases of mitosis and meiosis. Development of germ cells in plants and animals. The similarities and differences between mitosis and meiosis, their significance. Cell division is the basis for the growth, development and reproduction of organisms. The role of meiosis in ensuring the constancy of the number of chromosomes in generations
Terms and concepts tested in the examination paper: anaphase, gamete, gametogenesis, cell division, cell life cycle, zygote, interphase, conjugation, crossing over, meiosis, metaphase, ovogenesis, testis, sperm, spore, telophase, ovary, structure and function of chromosomes.
Chromosomes - cell structures that store and transmit hereditary information. A chromosome is made up of DNA and protein. The complex of proteins associated with DNA forms chromatin... Proteins play an important role in the packaging of DNA molecules in the nucleus. The chromosome structure is best seen in the metaphase of mitosis. It is a rod-shaped structure and consists of two sister chromatidsheld by the centromere in the area primary constriction... The diploid set of chromosomes of an organism is called karyotype ... Under the microscope, it can be seen that the chromosomes have transverse stripes that alternate in different chromosomes in different ways. Pairs of chromosomes are recognized, taking into account the distribution of light and dark stripes (alternation of AT and GC - pairs). The chromosomes of representatives have transverse striation. different types... Related species, such as humans and chimpanzees, have a similar pattern of striping in chromosomes.
Each type of organism has a constant number, shape and composition of chromosomes. In the human karyotype, there are 46 chromosomes - 44 autosomes and 2 sex chromosomes. Males are heterogametic (sex chromosomes XY) and females are homogametic (sex chromosomes XX). The Y chromosome differs from the X chromosome in the absence of some alleles. For example, there is no coagulation allele in the Y chromosome. As a result, only boys usually get hemophilia. Chromosomes of one pair are called homologous. Homologous chromosomes at the same loci (locations) carry allelic genes.
Cell life cycle. Interphase. Mitosis. Cell life cycle - this is the period of her life from division to division. Cells multiply by doubling their contents and then dividing in half. Cell division underlies the growth, development and regeneration of tissues in a multicellular organism. Cell cycle subdivided into interphase, accompanied by the exact copying and distribution of genetic material and mitosis - the actual cell division after doubling of other cellular components. The duration of cell cycles in different species, in different tissues and at different stages varies widely from one hour (in the embryo) to a year (in the liver cells of an adult).
Interphase - the period between two divisions. During this period, the cell prepares for division. The amount of DNA in chromosomes doubles. The number of other organelles doubles, proteins are synthesized, and the most active of them are those that form the spindle of division, the cell grows.
By the end of the interphase, each chromosome consists of two chromatids, which during mitosis will become independent chromosomes.
Mitosis Is a form of division of the cell nucleus. Therefore, it occurs only in eukaryotic cells. As a result of mitosis, each of the formed daughter nuclei receives the same set of genes that the parent cell had. Both diploid and haploid nuclei can enter mitosis. During mitosis, nuclei of the same ploidy as the original are obtained. Mitosis consists of several successive phases.
Prophase... Doubled centrioles diverge to different poles of the cell. From them to the centromeres of chromosomes, microtubules extend, forming a division spindle. Chromosomes are thickened and each chromosome is composed of two chromatids.
Metaphase... In this phase, chromosomes are clearly visible, consisting of two chromatids. They line up along the equator of the cell, forming a metaphase plate.
Anaphase... Chromatids diverge to the poles of the cell at the same speed. The microtubules are shortened.
Telophase... Daughter chromatids approach the cell poles. Microtubules disappear. The chromosomes are despiralized and again become filiform. The nuclear envelope, nucleolus, ribosomes are formed.
Cytokinesis - the process of separation of the cytoplasm. The cell membrane in the central part of the cell is pulled inward. A fission groove is formed, as it deepens, the cell bifurcates.
As a result of mitosis, two new nuclei are formed with identical sets of chromosomes that exactly copy the genetic information of the maternal nucleus.
In tumor cells, the course of mitosis is disrupted.
EXAMPLES OF TASKS
Part A
A1. Chromosomes are composed of
1) DNA and protein 3) DNA and RNA
2) RNA and protein 4) DNA and ATP
A2. How many chromosomes does a human liver cell contain?
1) 46 2) 23 3) 92 4) 66
A3. How many strands of DNA does a doubled chromosome have?
1) one 2) two 3) four 4) eight
A4. If a human zygote contains 46 chromosomes, then how many chromosomes are there in a human egg cell?
1) 46 2) 23 3) 92 4) 22
A5. What is the biological meaning of chromosome duplication in the interphase of mitosis?
1) In the process of doubling, hereditary information changes
2) Doubled chromosomes are better visible
3) As a result of chromosome doubling, the hereditary information of new cells remains unchanged
4) As a result of chromosome doubling, new cells contain twice as much information
A6. In which phase of mitosis does chromatids diverge to the poles of the cell? AT:
1) prophase 3) anaphase
2) metaphase 4) telophase
A7. Indicate the processes occurring in the interphase
1) the divergence of chromosomes to the poles of the cell
2) protein synthesis, DNA replication, cell growth
3) the formation of new nuclei, cell organelles
4) despiralization of chromosomes, formation of a division spindle
A8. As a result of mitosis,
1) genetic diversity of species
2) the formation of gametes
3) crossing chromosomes
4) germination of moss spores
A9. How many chromatids does each chromosome have before it doubles?
1) 2 2) 4 3) 1 4) 3
A10. As a result of mitosis,
1) zygote in sphagnum
2) sperm in a fly
3) oak buds
4) eggs in sunflower
Part B
IN 1. Select the processes occurring in the interphase of mitosis
1) protein synthesis
2) a decrease in the amount of DNA
3) cell growth
4) duplication of chromosomes
5) chromosome discrepancy
6) nuclear fission
AT 2. Indicate the processes underlying mitosis
1) mutations 4) sperm formation
2) growth 5) tissue regeneration
3) crushing the zygote 6) fertilization
OT. Establish the correct sequence of phases of the cell life cycle
A) anaphase B) telophase D) metaphase
B) interphase D) prophase E) cytokinesis
Part FROM
C1. What is common between the processes of tissue regeneration, the growth of the organism and the fragmentation of the zygote?
C2. What is the biological meaning of chromosome duplication and the amount of DNA in the interphase?
Meiosis... Meiosis is the process of division of cell nuclei, leading to a halving of the number of chromosomes and the formation of gametes. As a result of meiosis, four haploid cells (n) are formed from one diploid cell (2n).
Meiosis consists of two consecutive divisions, which are preceded by a single DNA replication in the interphase.
The main events of the prophase of the first meiotic division are as follows:
- homologous chromosomes unite along their entire length or, as they say, conjugate. When conjugated, chromosome pairs are formed - bivalents;
- as a result, complexes are formed consisting of two homologous chromosomes or of four chromatids (think, what is it for?);
- at the end of the prophase, crossing over (cross) occurs between homologous chromosomes: chromosomes exchange homologous regions with each other. It is crossing over that provides a variety of genetic information that children receive from their parents.
In metaphase I chromosomes line up along the equator of the division spindle. The centromeres face the poles.
Anaphase I - the threads of the spindle contract, homologous chromosomes, consisting of two chromatids, diverge to the poles of the cell, where haploid sets of chromosomes are formed (2 sets per cell). At this stage, chromosomal recombinations occur, which increase the degree of variability of the offspring.
Telophase I - cells with haploid set of chromosomes and twice the amount of DNA. A nuclear envelope is forming. Each cell contains 2 sister chromatids connected by a centromere.
The second division of meiosis consists of prophase II, metaphase II, anaphase II, telophase II, and cytokinesis.
Biological significance meiosis consists in the formation of cells participating in sexual reproduction, in maintaining the genetic constancy of species, as well as in sporulation in higher plants. Spores of mosses, ferns and some other groups of plants are formed by the meiotic pathway. Meiosis serves as the basis for the combinative variability of organisms. Violations of meiosis in humans can lead to pathologies such as Down's disease, idiocy, etc.
Development of germ cells.
The process of formation of germ cells is called gametogenesis. In multicellular organisms, spermatogenesis is distinguished - the formation of male germ cells and oogenesis - the formation of female germ cells. Consider the gametogenesis that occurs in the gonads of animals - the testes and ovaries.
Spermatogenesis - the process of transformation of diploid precursors of germ cells - spermatogonia into the sperm.
1. Spermatogonia are divided into two daughter cells - spermatocytes of the first order.
2. Spermatocytes of the first order are divided by meiosis (1st division) into two daughter cells - spermatocytes of the second order.
3. Spermatocytes of the second order proceed to the second meiotic division, as a result of which 4 haploid spermatids are formed.
4. Spermatids, after differentiation, turn into mature sperm.
The sperm cell consists of a head, neck and tail. He is mobile and due to this the likelihood of meeting him with gametes increases.
In mosses and ferns, sperm develop in antheridia, in angiosperms, they are formed in the pollen tubes.
Ovogenesis - the formation of oocytes in females. In animals, it occurs in the ovaries. In the breeding zone, there are ovogonia - the primary sex cells that multiply by mitosis.
After the first meiotic division, oocytes of the first order are formed from ovogonia.
After the second meiotic division, oocytes of the second order are formed, from which one egg and three directional bodies are formed, which then die. The eggs are motionless, spherical in shape. They are larger than other cells and contain a supply of nutrients for the development of the embryo.
In mosses and ferns, eggs develop in archegonia, in flowering plants, in ovules localized in the ovary of a flower.
EXAMPLES OF TASKS
Part A
A1. Meiosis is a process
1) changes in the number of chromosomes in the cell
2) doubling the number of chromosomes in a cell
3) gamete formation
4) conjugation of chromosomes
A2. At the heart of the change in the hereditary information of children
compared to parent information, processes lie
1) doubling the number of chromosomes
2) reducing the number of chromosomes by half
3) doubling the amount of DNA in cells
4) conjugation and crossing over
A3. The first division of meiosis ends with the formation:
2) cells with a haploid set of chromosomes
3) diploid cells
4) cells of different ploidy
A4. As a result of meiosis, the following are formed:
1) fern spores
2) cells of the walls of the fern antheridium
3) cells of the walls of archegonia fern
4) somatic cells of bee drones
A5. The metaphase of meiosis from the metaphase of mitosis can be distinguished by
1) the location of bivalents in the equatorial plane
2) duplication of chromosomes and their twisting
3) the formation of haploid cells
4) divergence of chromatids to the poles
A6. The telophase of the second division of meiosis can be recognized by
1) the formation of two diploid nuclei
2) the divergence of chromosomes to the poles of the cell
3) the formation of four haploid nuclei
4) doubling the number of chromatids in the cell
A7. How many chromatids will be contained in the nucleus of a rat sperm if it is known that the nuclei of its somatic cells contain 42 chromosomes
1) 42 2) 21 3) 84 4) 20
A8. The gametes formed as a result of meiosis enter
1) copies of the complete set of parental chromosomes
2) copies of a half set of parental chromosomes
3) a complete set of recombined parental chromosomes
4) half of the recombined set of parental chromosomes
Part B
IN 1. The biological significance of meiosis lies in maintaining the constancy of the species number of chromosomes, creating conditions for combinative variability; arbitrary divergence of parental chromosomes in gametes; preserving parental hereditary information without changes; increasing the number of chromosomes in a cell; preserving useful characteristics of the organism during reproduction
AT 2. Establish a correspondence between the process and the events that occur during this process
OT. Establish the correct sequence of processes occurring in meiosis
A) Location of bivalents in the equatorial plane
B) Formation of bivalents and crossing over
B) Divergence of homologous chromosomes to the poles of the cell
D) the formation of four haploid nuclei
E) the formation of two haploid nuclei containing two chromatids
Part C
C1. Meiosis underlies combinative variability. How can this be explained?
C2. Compare the results of mitosis and meiosis
This handbook contains all the theoretical material on the biology course required for passing the exam. It includes all the elements of the content, verified by control and measuring materials, and helps to generalize and systematize knowledge and skills for the course of secondary (full) school.
The theoretical material is presented in a concise, accessible form. Each section is accompanied by sample test items to test your knowledge and degree of preparation for the certification exam. Practical assignments correspond to the USE format. At the end of the manual, there are answers to tests that will help schoolchildren and applicants test themselves and fill in the gaps.
The manual is addressed to schoolchildren, applicants and teachers.
Examples.
Embryology studies
1) development of the organism from zygote to birth
2) the structure and function of the egg
3) postpartum human development
4) development of the body from birth to death
Breeding as a science solves problems
1) creation of new varieties of plants and animal breeds
2) preservation of the biosphere
3) creating agrocenoses
4) creating new fertilizers
Taxonomy is the science of
1) study external structure organisms
2) study of body functions
3) identifying connections between organisms
4) the classification of organisms.
The video course "Get an A" includes all the topics necessary to successfully pass the exam in mathematics at 60-65 points. Completely all tasks 1-13 Profile exam mathematics. Also suitable for passing the Basic exam in mathematics. If you want to pass the exam for 90-100 points, you need to solve part 1 in 30 minutes and without mistakes!
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G.I. Lerner
Biology
Complete guide to prepare for the exam
The Unified State Exam is a new form of certification that has become mandatory for high school graduates. Preparation for the Unified State Exam requires students to develop certain skills in answering the proposed questions and skills in filling out examination forms.
This comprehensive biology guide provides all the materials you need to prepare for the exam well.
1. The book includes theoretical knowledge of basic, advanced and high level knowledge and skills.
3. The methodological apparatus of the book (examples of assignments) is focused on testing the knowledge and certain skills of students in applying this knowledge both in familiar and in new situations.
4. The most difficult questions, the answers to which cause difficulties for students, are analyzed and discussed in order to help students cope with them.
5. The sequence of presentation of the educational material begins with "General Biology", tk. the content of all other courses in the examination work is based on general biological concepts.
At the beginning of each section, the CMMs for that section of the course are cited.
Then the theoretical content of the topic is presented. After that, examples of test items of all forms (in different proportions) encountered in the examination work are offered. Particular attention should be paid to terms and concepts that are italicized. They are, in the first place, checked in examination papers.
In a number of cases, the most difficult issues are analyzed and approaches to their solution are proposed. Answers to Part C contain only elements of the correct answer that will allow you to clarify information, supplement it, or provide other reasons for your answer. In all cases, these answers are sufficient to pass the exam.
The proposed tutorial in biology is addressed primarily to schoolchildren who decide to take the unified state exam in biology, as well as to teachers. At the same time, the book will be useful to all schoolchildren of the secondary school, because will allow not only to study the subject within the school curriculum, but also to systematically check its mastery.
Biology is the science of life
1.1. Biology as a science, its achievements, research methods, connections with other sciences. The role of biology in human life and practice
Terms and concepts tested in the examination papers for this section: hypothesis, research method, science, scientific fact, object of research, problem, theory, experiment.
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