Chromosomes (Greek Chroma Color, Color + Soma Body) - The main structural-functional elements of the cell nucleus containing genes located in linear manner and providing storage, reproduction of genetic information, as well as the initial stages of its implementation in signs; Change their linear structure in the cell cycle. The term "chromosomes" is proposed by Valteer (Waldeyer) in 1888 due to a row-shaped and intensive staining of these elements with the main dyes during cell division.
The term "chromosome" in its full meaning is applicable to the corresponding nuclear structures of cells of multicellular eukaryotic organisms (see). In the kernel of such cells, chromosomes are always several, they constitute a chromosomal set (see). In the somatic cells of the chromosomes of the guy, as they occur from two parents (diploid set of chromosomes), in mature genital cells contain a single (haploid) chromosome set. Each biological species is characterized by a constant number, dimensions and other morphological signs of chromosomes (see karyotype). In all-choice organisms, the chromosomal set includes two chromosomes that carry genes that determine the floor of the individual (see gene, gender), which are called sexual, or gonomas, as opposed to all other, called autosomas. A person has a pair of sex chromosomes: in women from two X chromosomes (XX set), and in men from X and Y-chromosome (XY set). Therefore, in mature genital cells - govetakes, women contain only X-chromosome, while men have half of the spermatozoa contains a X-chromosome, and the other - y-chromosome.
History
The first observations of chromosomes in the core of the cell, made in the 70s of the 19th century I. D. Chistyakov, O. Gerty, Strasburger (E. Strasburger), marked the beginning of the cytological direction in the study of chromosomes. Until the beginning of the 20th century, this direction was the only one. The use of a light microscope made it possible to obtain information on the behavior of chromosomes in mitotic and meiotic divisions (see Meiosis, Mitosis), facts about the constancy of the chromosome number from this species, special types of chromosomes. In the 20s of the 20th year of the 20th century, a comparative morphological study of chromosomes was obtained preferential development in different types of organisms, including a person, in order to clarify the general principles of their organization, features of individual chromosomes and changes in their evolution. In the study of this problem, domestic scientists S. G. Navashin, G. A. Levitsky, L. N. Delone, P. I. Zhivago, A. G. Andres, M. S. Navashin, A. A. P Rocofeeva-Belgovskaya, as well as foreign - Heitz (E. Heitz), Darlington (S. D. Darlington), etc. From the 50s, an electronic microscope was used to study chromosomes. The study of morphological changes in chromosomes in the process of their genetic functioning began. In 1956, Tio (H. J. Tjio) and Levan (A. Levan) finally established the number of chromosomes in a person equal to 46, described their morphological signs in mitosis metaphase. Significant progress in the study of chromosomes was achieved in the 70s after the development of various methods of their coloring, which allowed to identify the heterogeneity of the structure of chromosomes in length in the meta phase of cell division.
Comparison of the behavior of chromosomes in meiotic division with the patterns of inheritance of signs (see Mendel law) laid the beginning of cytogenetic research. At the end of the 19th - early 20th century Setton (W. Sutton), Bovteri (TH. Boveri), Wilson (E. V. Wilson) were laid the foundations of the chromosomal theory of heredity (see), according to which the genes are localized in chromosomes and the behavior of the latter The ripening of heamers and their merger at the time of fertilization explains the laws of transmission of signs in generations. The theory received a final substantiation in cytogenetic experiments conducted on Drozophile (see) T. Morgan and his students who have proven that each chromosome is a group of genes captured inherited and located in a linear manner that gene recombination is carried out in MEIZE (see recombination ) Homologous (identical) chromosomes.
The study of the biochemical nature of chromosomes, begun in the 30s-40th years of the 20th century, was originally based on cytochemical qualitative and quantitative determination of the content of DNA, RNA and proteins in the nucleus. Since the 50s, photo and spectrometry (see spectrophotometry), X-ray-based analysis (see) and other physicochemical methods began to be used for these purposes.
Physical and chemical chromosome
The physico-chemical nature of chromosomes depends on the complexity of the organization of the biological species. Eukarot chromosome consists of a deoxyribonucleic acid molecule (see), histone and nonregistone proteins (see Histons), as well as ribonucleic acid (see). The main chemical component of chromosomes entering into the structure of its molecule genetic information is DNA. In natural conditions, in certain sections of DNA chromosome, it may be free from structural proteins, but it mainly exists in the form of a complex with histones, both in the interfax and in metaphase, the weight ratio of the DNA / Histon is one. The content of acidic proteins in chromosomes varies depending on their activity and the degree of condensation in the cell cycle. In chromatin (see) the interphase nucleus and at any stage of mitotic condensation, DNA exists in a complex with histones, and the interaction of these molecules creates elementary structural particles of chromatin - nucleosome. In the nucleosome, its central part is 8 histone molecules of four types (2 molecules from each type). These are histones H2A, H2B, NZ and H4, interacting with each other, apparently, the C-terminal areas of molecules. N-terminal areas of histone molecules interact with a DNA molecule in such a way that the latter turns out to be coated on the histone ease, making two turns on one side of it and one to another. One nucleosome accounts for about 140 pairs of DNA bases. Between adjacent nucleosums there is a varies on the length of the length of the DNA (10-70 pairs of bases). When it is straightened, DNA takes the type of thread with beads. If the segment is in the folded state, the nucleosomes are closely adjacent to each other, forming a fibril with a diameter of 10 nm. The structure of nucleosomal particles is the principle of organizing the chromatin (see) both in the interphase and metaphase chromosome.
Individually distinguishable chromosomes are formed by the time of cell division, mitosis or meiosis, as a result of progressively increasing condensation by chromosomes. In the protopase of mitotic division of chromosomes, they are visible in a light microscope in the form of long and twisted threads, so individual chromosomes throughout indistinguishable. In the protopase of the first meiotic division of chromosomes, complex specific morphological transformations are undergoing mainly with the conjugation of homologous chromosomes (see the conjugation of chromosomes) and genetic recombination (exchanging sites) between them. In Patchithee (when conjugation ends), the alternation of the chromomer along the length of chromosomes is especially significant, and the chromomeric pattern is specific for each chromosome and changes as the condensation. Many chromosome in oogenesis and y-chromosome in spermatogenesis have high transcriptional activity. In some types of organisms, such chromosomes were called "tube brushes". They consist of an axis constructed from chromomer and interchromomeric sites, and numerous lateral loops - decondes of chromomer in a state of genetic functioning (transcription).
In the chromosome cell division metaphase, they have the smallest length and are easy to investigate, therefore the description of individual chromosomes, like all their sets in the cell, is given in relation to their state in this phase. The size of the metaphase chromosomes in the same type of organisms is highly different: chromosomes with dimensions in the shares of the micron have a point look, with a length of more than 1 microns, they look like rod-shaped bodies. It is usually split in length of formation consisting of two nursing chromatids (Fig. 2, 3), since chromosome metaphase is reduced.
Individual chromosomes of the set differ in length in length and other morphological features. The methods used until the 70s ensured uniform staining of the chromosome at its length. Nevertheless, such a chromosome as a mandatory element of the structure has a primary drawing - a plot where both chromatids are narrowed, apparently not separating one from the other, and poorly stained. This chromosome area is called centromer, it contains a specialized structure - a kinetchor, which is involved in the formation of the threads of the chromosome filament. According to the ratio of the size of the chromosome chromosomes lying on both sides, the chromosome shoulders are divided into three types: meticenteric (with a medianized suspension), submetrical (hauling is shifted from the middle), acrocentric (centromer is located close to the end of the chromosome, Fig. 3). A person has all three types of chromosomes. Chromosome ends are called telomeres. The length of chromosomes with one degree or another consistency may not have a relationship with the centromere, the so-called secondary tugs. If they are located close to the telomere, separated by a hawk distal sector of chromosomes are called a satellite, and a satellite bleeding (Fig. 2). In humans, ten with a secondary hawk chromosome, they are all acrocentric, satellites are localized in a short shoulder. Some secondary bleeds contain ribosomal genes and are called exercise-forming, since due to their functioning in RNA products in the interphase kernel, nucleolus is formed (see). Other secondary tugs are formed by heterochromatic areas of chromosomes; A person from such a tug has the most pronounced aboutcentro-sinks in 1, 9 and 16 chromosomes.
The initial method of using the gyms dye and other chromosomal dyes gave a uniform painting along the entire length of the chromosome. Since the beginning of the 70s, a number of coloring methods and processing of metaphase chromosomes have been developed, which allowed to detect differentiation (division into light and dark bands) of the linear structure of each chromosome along its entire length: Q-coloring (q - from English Quinacrine Acryin), obtained from using acrycine, acryciniprite and other fluorochromes; G-painting (G - from the Giemsa surname), obtained by a gym dye (see Romanovsky - GIMZ methods) after incubation of chromosomes in special conditions; R-coloring (R - from English Reverse Reverse; chromosomes are painted back G-color). The chromosome body turns out to be divided into segments of different intensity of staining or fluorescence. The number, position and size of such segments are specific for each chromosome, so any chromosomal set can be identified. Other methods allow differentially painting the individual specific areas of chromosomes. It is possible to selectively staining with the gimbal of the heterochromatic areas of chromosome (C-color; C - from the centromere of a centromer), located next to the centromer - C-segments (Fig. 4). The human segments have found in the near centromerous area of \u200b\u200ball outosomes and the long shoulder y -chromosomes. The heterochromatic areas vary largest in different individuals, caused by chromosome polymorphism (see chromosomal polymorphism). Specific coloring makes it possible to reveal in metaphase chromosomes functioning nuclei-forming areas in the Interfase, as well as the kinetokhory.
On the electronic microscopic level, the main ultrastructure unit of an interphase chromatin with translucent electron microscopy (see) is a diameter of 20-30 nm. The density of the packing of the threads is different in the plots of dense and diffuse chromatin.
The metaphase chromosome on a cut in a translucent electron microscope seems to be uniformly filled with fibrils 20-30 nm in the diameter, which, depending on the cross section plane, have a view of rounded, oval or elongated formations. In the proofased and bondage in chromosome, thicker threads can be detected (up to 300 nm). At electron microscopy, the surface of the metaphase chromosome is represented by chaotic laid numerous fibrils of different diameters, visible, as a rule, on a short segment (Fig. 5). Threads with a diameter of 30-60 nm prevail.
The variability of chromosomes in ontogenesis and evolution
The constancy of the chromosome number in the chromosomal set and the structure of each chromosome is the indispensable condition for normal development in ontogenesis (see) and the preservation of biol. species. During the life of the body, changes can occur by the number of individual chromosomes and even their haploid sets (genomic mutations) or the structure of chromosomes (chromosomal mutations). Unusual embodiments of chromosomes that determine the uniqueness of the chromosomal set of an individual are used as genetic markers (marker chromosomes). Genomic and chromosomal mutations play an important role in the evolution of biol. species. The data obtained in the study of chromosomes make a great contribution to the systematics of species (cariostematics). In animals, one of the main mechanisms of evolution variability is the change in the number and structure of individual chromosomes. The change in the content of heterochromatin in individual or several chromosomes is also important. A comparative study of human chromosome and modern human-like monkeys made it possible on the basis of similarity and differences with individual chromosomes to establish the degree of phylogenetic kinship of these species and simulate the karyotype of their common nearest ancestor.
Bockov N. P., Zakharov A. F. and Ivanov V. I. Medical Genetics, M., 1984; Darlington S. D. and La Court L. F. Chromosome, work methods, per. from English, M., 1980, bibliogr.; Zakharov A. F. Chromosome of a person (problems of a linear organization;, M., 1977, Bibliogr.; Zakharov A. F. and others. Human chromosomes, Atlas, M., 1982; Kikanadze I. I. Functional organization Chromosome, L. , 1972, Bibliogr.; Basics of human cytogenetics, ed. A. A. Prokofyeva-Belgovskaya, M., 1969: Swonzo N K., Merez T. and Yang W. Citogenetics, Per. From English, M., 1969 ; Cell Biology, A Comprehensive Treatise, ED. By L. Goldstein a. Dm Prescott, p. 267, NY AO, 1979; Seuanez H. N, The Phylogeny of Human Chromosomes, v. 2, B. AO 1979; Sharm A AK a. Sharma A. Chromosome Techniques, L. Ao, 1980; Thermane. Human Chromosomes, NY AO, 1980.
A. F. Zakharov.
Chromosome - the most important cell element. They are responsible for the transfer and implementation of hereditary information and in the eukaryotic cell are localized in the kernel.
The chemical structure of the chromosome is complexes of deoxyribonucleic acids (DNA) and associated proteins, as well as a small number of other substances and ions. Thus, chromosome are deoxyribonucleoproteides (DNP).
Each chromosome in the interfase includes one long double-stranded DNA molecule. The gene is a sequence of a certain amount of nucleotide of DNA follows each other. The genes included in the DNA of the same chromosome are followed by each other. In an interfass in the cell, many processes proceeds, many sections of chromosomes are despirate to varying degrees. Many DNA sites are the synthesis of RNA.
During the period of cell division (both during mitosis and during meyosis), chromosome spirals (compaction them occurs). At the same time, their length is reduced, and the synthesis on them RNA becomes impossible. Each chromosome doubles to spiralization. It is said that the chromosome becomes consisting of two chromatid. That is, during the interphase period, the chromosome consisted of one chromatide.
In compactization, chromatide is an important role is played by the proteins that are part of the chromosome.
Thus, depending on the phase of the cell cycle on the external structure of the chromosome, 1) may be represented as invisible in the light microscope chromatina (in interfass) and consist of one chromatide or 2) in the form of two spiralized chromatids visible to the light microscope (in the cellular division phases, starting with metafase).
In the structure of chromosomes there is another important element - centrometer (primary hauling). It has a protein nature and is responsible for the movement of the chromosome, and the fasteners of the fission are attached to it. Depending on the location of the center, the centrners distinguish equalion (meticenter), non-equal control (submetrical) and chromium-shaped (acrocentric) chromosomes. In the first centromer is located in the middle, separating every chromatide into two equal shoulders, in the second shoulders of unequal length, and the third centromer is located at one of the ends of chromatide.
In double chromosomes, chromatids are interconnected in the field of centromers.
The structure of the twin chromosome.
1 - chromatide; 2 - centromer; 3 - short shoulder; 4 - Long shoulder.
The presence of primary drying in the structure of chromosomes is required. However, besides them there are secondary hats ( emergency organizers), they are not observed in all chromosomes. In the core on the secondary halves of chromosomes, the synthesis of nucleols occurs.
At the ends chromatids are so-called telomeres. They interfere with chromosomes sticking.
In the haploid set, each chromosome is unique in its structure. The position of the centrometers (and caused by these lengths of the shoulders of chromosomes) allows you to distinguish each among the others.
In the diploid set, each chromosome has a homologous to it, having the same structure and the same set of genes (but perhaps other alleles of their alleles) and has taken from another parent.
For each type of living organisms, its karyotype is characteristic, i.e., its number of chromosomes and their features (length, centromer, characteristics of the chemical structure). By karyotype, you can define a biological view.
Lecture number 3.
Topic: Organization of the flow of genetic information
Plan lectures
1. The structure and functions of the cell nucleus.
2. Chromosome: Structure and classification.
3. Cell and mitotic cycles.
4. Mitosis, Meiosis: Cytological and cytogenetic characteristics, value.
The structure and functions of the cell nucleus
The main genetic information is enclosed in the core of the cells.
Cell kernel (Lat. - nucleus.; Greek. - karyon.) It was described in 1831. Robert Brown. The shape of the nucleus depends on the shape and functions of the cell. The sizes of cores vary depending on the metabolic activity of cells.
An interphase core sheath (caryolamma) Consists of outer and internal elementary membranes. Between them is perinuclear space. In the membranes there are holes - pores.Between the edges of the nuclear pore are protein molecules that form pore complexes. The pore hole is closed with a thin film. With active metabolic processes in the cell, most pores are open. Through them there is a stream of substances - from the cytoplasm in the kernel and back. Number of pores in one nucleus
Fig.The scheme of the structure of the cell core
1 and 2 - the outer and inner membrane of the nuclear shell, 3
- Nuclear time, 4 - Yadryshko, 5 - Chromatin, 6 - nuclear juice
reaches 3-4 thousand. The outer nuclear membrane is connected to the channels of the endoplasmic network. It usually arranges ribosomes. The proteins of the inner surface of the nuclear shell form nuclear plate. It supports the constant shape of the nucleus, chromosomes are attached to it.
Nuclear Juice - Kariolimf, colloidal solution in the state of the gel, which contains proteins, lipids, carbohydrates, RNA, nucleotides, enzymes. Nadryshko - non-permanent kernel component. It disappears at the beginning of cell division and is restored at the end of it. Chemical composition of nucleolus: protein (~ 90%), RNA (~ 6%), lipids, enzymes. The nuclei are formed in the field of secondary pigeons of satellite chromosomes. The function of the nucleus: assembly of subunit ribosomes.
H. roman The nuclei is the interphase chromosomes. They contain DNA, proteins-histones and RNA in a ratio of 1: 1.3: 0.2. DNA in connection with protein forms deoxyribonucleoprotein (DNP). With mitotic division of the NDP kernel spiral and forms chromosome.
Functions of the cell kernel:
1) keeps the hereditary information of the cell;
2) participates in division (reproduction) cells;
3) regulates the metabolic processes in the cell.
Chromosome: Structure and Classification
Chromosomes (Greek - - chromo. - color, soma. - Body) is spiralized chromatin. Their length is 0.2 - 5.0 μm, diameter 0.2 - 2 microns.
Fig.Types chromosomes
Methazna chromosome Consists of two chromatidwhich are connected centromer (primary drawing). She divides chromosomes for two shoulder. Separate chromosomes have secondary drying. The site that they separate is called satellite, and such chromosomes - satellite. End plots chromosomes are called telomeres. Each chromatide includes one continuous DNA molecule in a combination with Histon proteins. Intensively staining sections with chromosomes are plots of strong spiralization ( heterochromatin). Lonely sections - sections of weak spiralization ( eukhromatin).
Types of chromosomes are isolated by the location of centromers (Fig.).
1. Metic centers chromosomes - Centrome is located in the middle, and the shoulders have the same length. The shoulder section near the centrometers is called proximal, opposite - distal.
2. Sublesstritic chromosomes - The centride is shifted from the center and shoulders have different lengths.
3. Acrocentric chromosomes - The centromer is strongly shifted from the center and one shoulder is very short, the second shoulder is very long.
In the cells of the salivary glands of insects (flies of drosophyl) there are gigantic, polluted chromosomes (Multi-grated chromosomes).
For chromosomes of all organisms there are 4 rules:
1. Rule of constancy number chromosome. Normally, the organisms of certain species have a constant, characteristic of the type of chromosome. For example: Human 46, in a dog 78, in Fly Drozophila 8.
2. Pawn chromosomes. In the diploid set in the norm, each chromosome has a pair chromosome - the same in shape and largest.
3. Individuality chromosomes. Chromosome of different pairs differ in shape, structure and magnitude.
4. Continuity chromosomes. When doubling the genetic material of the chromosome is formed from chromosome.
A set of chromosome of a somatic cell characteristic of the body of this species is called karyotype.
Classification of chromosomes are carried out according to different features.
1. Chromosomes, the same in the cells of the male and female organisms, are called autosomas. In a person in the karyotype 22 pairs of autos. Chromosomes, various in the cells of the male and female organisms are called heterochromosomes, or sex chromosomes. In a man, it is X and Y chromosome, in women - X and H.
2. The location of chromosomes in a decreasing value is called idiogram. This is a systematized karyotype. Chromosome are placed in pairs (homologous chromosomes). The first pair is the largest, 22th pair - the small and 23rd pair - sex chromosomes.
3. In 1960. Denver classification of chromosomes was proposed. It is built on the basis of their shape, sizes, positions of centromeres, the presence of secondary drawings and satellites. An important indicator in this classification is centering Index (Qi). This is the ratio of the short shoulder length of the chromosome to its entire length, expressed in percent. All chromosomes are divided into 7 groups. Groups are denoted by Latin letters from A to G.
Group A. Includes 1 - 3 pairs of chromosomes. These are large meticenter and submetrical chromosomes. They are 38-49%.
Group B.. The 4th and 5th pairs are large meticenter chromosomes. Qi 24-30%.
Group S.. Couple chromosomes 6 - 12: medium, submetrical. Qi 27-35%. This group includes x-chromosome.
Group D.. 13 - 15th pairs of chromosomes. Chromosome acrocentric. Qi about 15%.
E. Group. Couple chromosomes 16 - 18. Comparatively short, meticenter or submetrical. Qi 26-40%.
Group F.. 19 - 20th Couples. Short, submetrical chromosomes. Qi 36-46%.
Group G.. 21-22 pages. Small, acrocentric chromosomes. Qi 13-33%. This group includes y-chromosome.
4. Paris classification of a man chromosoma was created in 1971. With this classification, it is possible to determine the localization of genes in a certain pair of chromosomes. Using special coloring methods, each chromosome detects the characteristic procedure for the alternation of dark and light strips (segments). Segments are denoted by the names of the methods that detect them: q - segments - after staining with acryoine-iprit; G - segments - painting by the gymnus dye; R - segments - staining after thermal denaturation and others. The short shoulder chromosome is denoted by the letter P, the long - letter Q. Each shoulder chromosomes are divided into areas and denote numbers from centromers to the Telomer. The strips inside the areas are numbered in order from the centromere. For example, the arrangement of the Esterase D - 13P14 gene is the fourth strip of the first district of the 13th chromosome.
Function chromosomes: storage, reproduction and transmission of genetic information in the reproduction of cells and organisms.
Similar information.
The chromosomal set of a person carries not only hereditary signs, as written in any textbook, but also the karmic debts that can manifest themselves as hereditary diseases, if the person in the time of their presentation for the payment did not have time to change its mistaken perception of reality, thereby extinguished by another debt. In addition, a person could distort the chromosome not only the mistakes of his worldview, but also in the wrong nutrition, lifestyle, finding or working in malicious places, etc. All these factors are additionally distorted by the human chromosomes, in which it is easy to make sure that the status studies are easily Chromosome, for example, on computer diagnostics Oberon. From the same diagnosis it can be seen that when healing the state of the chromosomal set of a person is improving. And the restoration of chromosomes and only partial occurs significantly later the restoration of the health of the organ or system of a person if the healing of a person was produced without studying the root causes. It means that the "blow of fate" of a man chromosome is the first to take over the "blow of the fate", which is then manifested at the cellular level, and then in the form of illness.
So, the accumulated "wealth" of errors is fixed in a person at the level of its chromosomes. Distortion in chromosomes closing or distorting super supervoloment of man and create illusion of fearbecause distort energy and information serve the cause of illusory perception of themselves, people and the surrounding world.
Large distortions in human chromosomes are pricking root causewhich arises due to the illusory perception of itself, starting with 12% distortion. Large distortions of the chromosomal set are usually inherent in sorcerers and a diverse public practicing magic (because there is little energy), NLP, Rake, hypnosis, Dianetics, Cosmoenergetics, "Channels". So professionals and ourselves constantly have to use this, because Otherwise, the cargo of the accumulated karma due to the use of malicious methods of adjusting problems into the future can and crush, the same can be said about unreasonable patients agreeing on the use of such methods.
The average chromosomal set distortion in people is 8%.
Each pair of chromosomes is responsible for its sphere of health and life. I will give data on the 5th, 8th, 17th and 22nd, since it is in them contained the main distortions (85% of 100%) in those who will be present at the session on April 19.
The 5th pair of chromosomes is responsible for childbearing, the relationship of floors, the transmission of generic energies, including karmic rewards on negative generic karma (Orc).
The 8th pair is responsible for immunity, cleansing from slags and toxins, lymphatic system, system of defecation and discharge (including sweat glands), urinary, kidney, liver, spleen, thin and large intestines.
The 17th couple is responsible for working out in the body of hormones, including endorphins, thyroid gland, pituitary gland, the entire endocrine system.
The 22nd pair is responsible for the musculoskeletal system and movement control (vestibular apparatus, middle ear and coordination violation), the production of lactic acid (fatigue), physical endurance of the body.
I will give examples:
- Athletes in the presence of distortions in the 22nd pair of chromosomes will never be able to achieve significant sporting achievements. More precisely, the magnitude of sports achievements is inversely proportional to distortions in the 22nd pair of chromosomes.
- The dancer will never become outstanding if it has distortions in the 5th and 22nd couples chromosomes.
Distortion in chromosomes are one of the main causes of changed cells.