For which the chromosomes are needed. The structure and functions of chromosomes. Reproduction in the organic world. The structure of genital cells. History of opening chromosomes

1. The structure of the mitotic chromosome. Types of chromosomes, their number, size. Karyotype and girogram. Human chromosome. Denver classification of man chromosomes.

In the primary hauling area, the centerier is located - this is a plate structure having a disc shape. It is associated with thin fibrils and chromosome body in the area of \u200b\u200bthe tank. Typically, the chromosome has only 1 centruller, but may occur dicentric and polycentric. Those k-e chromosomes have a secondary drawing, the K-I usually located near the distal end of the chromosome and separates a small portion - satellite. Secondary trigteles are called, in addition, nuclear organizers, because They have in these areas chromosomes in the interfase occurs the formation of nucleists. Here the DNA is localized responsible for the synthesis of r-RNA. Shrums chromosome ends with telomeres, end portions. The length of chromosomes can vary from 0.2 to 50mkm. The number of chromosomes in various objects fluctuates significantly, but is characteristic of the form of animals or plants. The totality of the number, quantity and morphology chromosomes is called a karyotype of this species. Ideogram - drawings or images of chromosomes located in a row in descending order. Such a simple morphological analysis can convincingly show differences in the karyotype even in close species. The exact number of human chromosome and the method of calculating their calculation in the leukocytes of peripheral blood was created in 1956. In 1959, an international classification of a man chromosoma was adopted, called Denver. According to this classification, all human chromosomes are divided into two unequal groups: 22 pairs of autosomes and a heterochromosa group includes sex chromosomes (XX and XY). Autosomes are distributed to 7 groups according to their size and morphology.

2. Meiosis his biol role, stage. Conjugation of the XP-M, Crossing Hoverer, the reduction of the number of XP-M. Hr-we type lamp shield. Difference M / in mitosis and meyosis.

In fertilization, the merge of the nuclei of parental cells must ensure that there should be an increase in twice the amount of DNA and chromosomes in the zygote and, accordingly, in all cells of the developing organism. Therefore, in the formation of genital cells, there must be a mechanism for reducing the number of chromosomes, which would compensate for the doubling of their set in fertilization. This is achieved with a special division of ripening genital cells, with reduction division in the process. mEIOSA,- which, as opposed to fertilization, leads to a decrease in the chromosome chromosome in the cell. It consists of 2 next other dr. Kernel fission and one doubling the number of DNA. It also occurs recombination of gene material, the exchange of m / in homologous chromosomes (crosslinker), activation of transcription in the first division program and the absence of the S-phase M / in the 1st 2 division. In the body there is a constant alternation of phases, excellent in the number of chromosomes on the cage. It - gaplophazarepresented by cells with the smallest Chr-M, and diplophase. in which there are cells with double, 2p.number of hrm. Depending on the situation in the life cycle of the development of organisms, 3 types of MEIOS: Cirogenic, govetaya, intermediate. Sigo (source) - Meiosis comes immediately after fertilization, in the zygote. At askomitzets, disputes, etc. Org-mov, in the life cycle cat prevails pphase. Can multiply without interchange.

Gametnaya - during the ripening of hemes, in multicellular animals, simple and ne-x lower plants, prevailing 2p.phase. P: Green algae which multiplies only with the help of the sexual process. Gaploid large female and small male games, merging, form a zygot, which germinates to a new diploid plant. In the future, with the development of the genital organs, Gamethangiev, a reduction division occurs, and haplid gametes are formed. Thus, the haplophaz here is significantly reduced.

Intermediate (dispute) at the highest rash, during a spore formation, including m / in the stages of Sporophyte and Gametophyte. In breeding bodies 2p.organisms occurs image-e n S. (microspores) and $ (megasy) genital cells. Honors from the previous type what after meiosis pcells are several times divided during reduced haplophazes. Harm for MEIOS is that during the first division opposite there is a special restructuring and arrangement of the XP-M in the nuclei of the ripening genital cells.

The first (i) meiotic division is divided into 5 stages: Leptoten - stage of thin threads, Zigoten - stage of merging threads, pachiten - stage of thick threads, diploten - stage of double threads, Diacines - the stage of separation of double threads. Then follows the metaphase I of division and the subsequent phases of cell division, the following n cycle occurs, in the final resort leading to the appearance of mature genital cl. The cells included in the meyosis have a normal diploid 2p number of XP-M and the amount corresponding to this number of DNA (2C). In the first cycle of the meiotic division, a normal S-phase occurs, leading to DNA doubling, i.e. CL contains 4P Number of Khr-m. Rave meyosis is much longer mitosis in time.

Leptoten - The stage of thin threads, resembles the early opposite of mitosis, but exceeds the fact that when the kernel meeise is larger and xp is very thin (so that it is very difficult to trace them along the entire length). In Leptoten, Khr-we doubled, but the nursing chromatids in them are not always possible to distinguish, so
there are 2P dual nursing chromatids, the total number of 4P due to the Redupplication in the S-period. On thin chromosomes, chromatin clot appears - chromomer, which is riveted in the form of beads along the entire length of the XP. This allows you to make Morphological maps of the XP-M and use for cytogenetic analysis. In Leptoten, the process of conjugation of homologous chromosomes begins in Leptoten.

Zigoten - Stage of passing the conjugation of homologous chr-m. At the same time, homologous XP-we (already double after the S-period) come closer and form a new XP-memball, never before that occurs during cellular division - bivalent. Bivalent is paired compounds of doubled homologous XP-M, i.e. Each bivalent consists of 4 chromatids. Thus, the number of bivalents on the kernel will be equal to the haploid number of chromosomes. Unlike mitosis, in the MEIOS PROFAZ, namely, a small number of specific DNA, called Z DNA, is synthesized. In the mitotic cycle, it is synthesized simultaneously with the main mass of DNA, but during meyosis - only in the zygothen stage. If you suppress the additional synthesis of DNA with inhibitors, then the conjugation of chromosomes will stop. Combining homologs most often begins in telomeres and centromers, occurs rapprochement of axial weights at a distance of about \u003d 100 nm, binders are formed between them, and this is the formation of the complete structure of the synaptonemal complex.

3. Pakhtene - Stage of thick threads, is called thanks to the complete conjugation of homologues, the profhaasic XP-we seem to have increased in thickness. The number of such thick dying chicted chr-M Haaploid-1P, but they consist of 2 united homologues, each of which consists of 2 nursing chromatids. At this stage, a crosslinker occurs, the mutual exchange of identical sites along the length of homologous XP-M. Here are different from the initial XP-we containing separate
sections that came from their homologues. In Patchithee, the synthesis of a small number of DNA (restoration of lost DNA) occurs. In the duplicate stage, the activation of the transcriptional ability of the XP-M begins, at this time $. The genital cells are amplified by ribosomal genes, which leads to the appearance of additional nucleols. At the same stage, some chromomers begin to activate and the structure of the XP-M is changed; They acquire the type of "lamp shield". Especially these changes are visible at the stage of dish.

4. Diplloten - The stage of double threads, there is a repulsion of homologs from each other in the center of the centerier, but at the same time a pair of nursing chromatids of each homologous XP-we remain connected by the M / in centromeds and along the entire length. As the HR-M repulsion in Bivalents, the choir is visible to the Hiazma - the place of the crossroads and the clutch of the XP-M. Only in these areas the structure of the synaptonemal complex is preserved, in the separated areas it disappears. In the diplotional stage of the XP-we acquire the type of "lamp shield". These strokes are found in oocytes and spermatocytes in all animals and plants. At the Khr-max of this stage, it is clear that every homolog in Bivalent is surrounded by a felt consisting of petroleum nital structures. At the same time, the loops are parosymmetric, and each pair departs from a chromomer located on a chromosomal axis. This axis is nothing more than two paired nursing chromatids, and chromomers are double sections of condensed chromatin, the loops are decondes of the active, functioning chromatin. The loops contain a large number of RNA, which is also synthesized here. This RNA refers in its characteristics to information. The loops of these XP-M are formed by a double-axis xp-me thread, on which multiple transcription points lie, from which the growing RNA molecules are deployed. The presence of active XP-M in the diploten sharply distinguishes meiosis from mitosis, where, starting from the opposis, the synthesis of RNA completely stops.

5. Diacines It is characterized by a decrease in the number of chiasm, shortening of bivalents, loss of nuclei. Bivalent acquire a more compact form. Xp-we lose ties with a nuclear shell. This stage is the transitional to the cell division itself. In Metaphase I, MEIOS division, bivalents are built in the Equatorial plane of the spindle

In AnafhaseI. D.the element is committed by the Chrm, but unlike mitosis, no sister chromatides are diverged, and homologous XP, consisting of 2 nursing chromatids. In anafase, in different cells, consumption of allelic genes, is located in different homologues. The distribution of homologues by cells is completely random, so that there is a mixing, reconventionation of the XP-M from different steam.

Following the Bulphasis I of division, a short interphase is followed in which the synthesis of DNA and CL are not occurring, which is not exceeded, which is not different from mitotic division by morphology: pair sister chromatides, connected in centromeds, pass proofas and metafase; In Anafase, they are disconnected and diverged by one to the subsidiaries. So With II MEYOTIC division of a cell with 2C Col-M DNAand 2p the number of chromatids, sharing, gives the beginning of two cells with pcontent DNAand Khr-m. The division of Maeiza Yavl-Xia is reduction. In the residence of the entire process of meiosis after 2 divisions of one CL, 4 haploid is formed, each of which differs in its genetic constitution.

Differences between mitosis and meyosis: - The presence of active chromosomes in the diploten sharply distinguishes Meiosis from mitosis, where, starting with the opposis, the synthesis of RNA completely stops.

in the anafase of 1 division, the chromosome is discrepaning., But unlike mitosis, no sister chromatides are diverged, but homologous chromosomes consisting of 2 nursing chromatids.

unlike mitosis in the MEIOS PROFACE, a small amount of specific is synthesized at the zygothen stage. DNA(Z-DNA). In mitotic division, it is synthesized simultaneously with the bulk of DNA.

in plants, Meiosis is much longer mitosis in time. So, at the tradescania, all Meiosis takes about 5 days, of which 4 days account for 1 division.

in case of meyosis, in addition to the reduction of the chromosome, a number of processes occur, distinguishing this type of division from mitosis. This is recombination of the genetic material, the exchange between homologous chromosomes (crosslinker).

maiz is characterized by activation of transcription in the first division protoz and the absence of the S-phase between 1 and 2 divisions.

3. Genetic recombination in prokaryotes. Bacteria conjugation. Final factor among intestinal sticks, his role. Plasmids, their role in transferring genetic information.

Genetic recombination-oversbiological phenomenon, characteristic of all living organisms, ranging from viruses and bacteria and ending with man. It is based on a complex enzyme process of interaction of nucleic acid molecules of two parents, leading to the redistribution of genes or their components and ultimately, to a change in the hereditary properties of the offspring. A large role of genetic recombination as one of the driving forces in the evolution of prokaryotes. Transmission of genetic information in microorganisms occurs through transformation, transduction and conjugation.

Conjugation-connection of the opposite sex cells (male F + and female F -) by means of protoplamic bridges through which during 1.5 h. The genetic material from donor cells into recyputes is transmitted. But the bacterial. higher organisms. This process can be divided into 5 stages: cell compound and the formation of a conjugation channel; a compound of homologous sections with chromosomes (synapis) and the formation of partial zygotes; The interaction of parental DNA molecules and the formation of recombinant structures; Segregation of stable haploid genomes. To establish cell contacts, it is necessary to have special genetic factors that Luria called the conjugon. Cell contact is a prerequisite for subsequent transmission of DNA and sex recombination.

Final factor in E. coli (Factor F)

To form recombinants, it is necessary to preserve the viability of one of the parents, while the other may die. This made it possible to distinguish two sexual type F + (donor or men's strains) and F - (women's strains). Recombinants from crossing F + XF - always belong to the type f +, acquiring

Factor f. For such an infectious transmission of Factor F into cells F - a cell contact (conjugation) is needed. The Factor F is due to its nature is DNA, the number of DNA in the factor F is similar to the DNA content in the bacteriophage.

Plasmids - extrachromosomic genetic elements of bacteria. Cell stability to the action of various damaging agents, their spontaneous and induced mutability, replication and recombination of chromosomal DNA are controlled by chromosomal and plasmid genes. Bacterial plasmids can carry genes responsible for a variety of signs of the host cell, including cell growth, RNA metabolism, carbohydrates and hydrocarbons, the formation of pigments and antibiotics.

4. The first and second laws of Mendel. Cytological substantiation of Mendel's laws. Principles of the hybridological method. Return and analyzing crossing. Incomplete dominance.

Hybridological method - 1865.- The basis of genetic analysis, created by Mendel. The essence is to study the inheritance of individual features and properties.

Characterized:

using the form of one species, characterized by a small number of features;

accurate accounting of the number of hybrid individuals is underway;

the offspring is analyzed individually from each individual.

Depending on which the number of features, cross-lucked individuals are distinguished, isolated mono-, di-, tri-, polygibrid crossing.

Features:

obtaining for several generations of constant forms, which were later crossed,

analysis of the inheritance of individual pairs of signs in the offspring of crossed plants of one species differing in one, two, three pairs of contrasting genes, alternative features (PR: flowers purple and white), in each generation, a separate account was conducted separately for each pair of alternative pr-in,

the use of the amount of hybrid plants, differing in individual parameters of alternative signs, in a series of consecutive generations,

the use of individual analysis of the offspring of each hybrid plant.

Mono-librid crossing - the domestic form differ in one pair of alternative signs. If the motherboard with purple flowers, paternal - with white, then the flowers of all hybrid plants F1 are purple, white color of flowers does not appear.

F1 hybrids from a pair of parental alternative signs develops only one, the second does not appear, the phenomenon of the prevalence of a hybrid F1 a sign of one of the parents of Mendel called it to dominance. The feature manifested in a hybrid is dominant, and the suppressed is recessive. The law of dominance (the first law of Mendel) is the law of uniformity, hybrids of the first generation. F1 hybrids were samped, then in the next generation (F2) plants appear with signs of both parents in a 3: 1 ratio. This ratio expresses the second law of Mendel, or the law splitting of the signs in the second generation hybrids in the 3: 1 ratio along the phenotype.

Allel is a different state of the same gene

Suppose, in somatic pea cells there is only one pair of homologous chromosomes, and alleles that determine the sign of purple painting (a) are in each of these chromosomes in parent plants. Then the somatic cells of the homozyotic plant with a dominant sign of the flower color must bear two dominant alleles AA due to the paired chromosomes. Cells of other parent plants with white flowers have recessive alleles aa in a homozygotic state. As a result of MEIOS, one chromosome from the pair and one allele - A (dominant) and A (recessive) remain in each gumet. As a result of fertilization in a hybrid zygote, a pair of chromosomes is restored, and the hybrid formula will be AA. When the genital cells are formed by a hybrid in the meyosis of chromosomes, it will be divided into different games, and the male and female gamets carrying on one of the allele of the gene A or A will be formed in an equal number. In fertilization, men's and female gamets of both types will be connected with equal to probability, as a result - splitting 1 AA: 2AAA: 1AA.

If a hybrid F1 of two allelic signs manifests one dominant, and in F2, the recessive is highlighted precisely in the same pure form, as the initial forms, which means heterosigons of the allele A and A. Do not mix. As a result, the gamete formed by such heterosigotes are "Clean" In the sense that gamet And "Clea" and does not contain from allele but, Gameta. and "Clea" from BUT. This phenomenon is not mixing alleles of alternative signs in Gybrid gates got the name "The Law of Purity Games".

Returning crossing This is a crossing of hybrids with one of the parental forms: such a crossing of a F1 hybrid with a form carrying this pair of alleles (dominant and recessive) in a homozygous state (return or bicked), and the offspring is denoted F.in

With a return crossing of a hybrid F1 AA Mixed form homozygous for dominant allele (AA), All Gamets Parental Plants will be carried by a dominant allele BUT, and hybrids F2 formed gametes of 2 types BUTand but. As a result of a random combination of these Games in the descendant, the discharge of genotype occurs 2AAA: 2AAA or 1:1 , the splitting of the phenotype is not observed

Hybrid crossing F1. AA With recessive homozygotoe (AA) You should expect cleavage of genotype and 1: 1 phenotype. Crossing a form with a dominant sign and forms with a recessive sign received name analyzing crossing. With the help of an analyzing crossing, you can check the genotype of the body of unknown origin. Analyzing crossing is a special return case.

Incomplete dominance (intermediate)

In some cases, the sign shows an intermediate expression in heterozygot when comparing it with both parental forms. Pr: When crossing the forms of night beauties with red and white flowers of hybrids have pink flowers.

A person has a blood illness - a passage, which manifests itself in two forms: big and small. Big manifests itself in recessive homozygot, small in heterozygot, healthy people are dominant heterozygots. In case of incomplete dominance, the splitting of the phenotype and genotype coincide and there is no need for an analyzing crossing.

5. Genetics of self-population populations. Selection of self-population. Pamptic populations, their dynamics. Hardy Weinberg law, the possibility of its use. Factors restricting this law.

The equilibrium frequencies of genotypes are the product of the corresponding alleles. If there are two alleles (A and A with frequencies p and q), the frequencies of three possible genotypes are expressed (P + Q) 2 \u003d P. 2 + 2 pq + q 2

This is a UR-E in 1908 sform. Hardy and Weinberg, according to the formula p. 2 + 2 pq + q 2 = 0 , Then knowing the frequency of recessive homozygotes can be calculated by the frequencies of all population genotypes.

Zn Hardy Weinberg never real-smiling in pure form, because On the population of Dista-T numerous. F-s, violating its genetic equilibrium. Such processes include mutations, migration, drift genes, eats. and art. Selection, waves of life.

Mutations- The only source is generated .. variability, but because of the only low frequency, it is changed. Stroke Population slowly.

Migration (gene flow) arise when moving individuals of one population in DR and crossing with its representatives. The flow of genes does not change the frequencies of alleles by the type as a whole, but in local population. They change.

Genov drift - changing the frequencies of alleles in a number of generations caused by the problem. reasons, most often in the small number of population.

Waves of Life - These are sharp fluctuations in the number of numbers, the cat. Periodic Har-p with different wavelengths or aperiodic, when the wave increases without signs of recession. time.

Eating. selection- the most important factor in evolution. Only it determines the adaptive value of percentage in mutagenesis, migration or drift of genes. It determines the variety of organisms and contributes to their adaptation to Split. Sl. creatures.

Assortive crossing- This is crossing when the choice of partner Ozaz. Influence of genotype.

7. Genetics floor. Sex chromosomes. Types of chromosomal floor definition. Homo - and heterogament floor. Inheritance adhesive with floor. Genetic analysis with this type of inheritance.

The floor is a set of morphological and physiological and physical properties of the body providing sexual reproduction, the body's ability produces sex cells of a certain sign - male and female, the merger of haploid gamietic - fertilizers - leads to the formation of a diploid couple from which a new organism develops.

Floor definition, i.e., the switching of cells into development in one case is female, and in another men's reproductive organs, in different species are carried out at different stages of individual development. The switching mechanism is not fully disclosed. The following types are distinguished:

genetic (progan - half of the offspring determines the genotype of the egg; Singoma - the floor is determined at the moment of fertilization depends on the sperm genotype)

phenotypic - epigamon, the floor is determined after fertilization, under the influence of environmental conditions.

The phenotypic determination of the floor is a rare thing, since the ratio between the floors, determined by the conditions of the medium, is not sustainable and not defined. The larvae, developing in contact with the trunk, turn into males, free in females.

The first data on the communication of the floor with chromosomes of the cell was obtained in 1902 when studying meiosis in herbal bedbugs. The males 2n \u003d 13 and 2n \u003d 14 in females. The study of the course of meiosis showed that males 13th chromosome differs from the rest of the larger sizes. The distribution of chromosomes occurred in such a way that half of the cells had (6 + x) chromium, and the second was (6 + 0), x - chromosome did not have. It is obvious that X - the chromosome has deviations to the definition of the floor, since the fusion of cells (6 + x) (6 + 0) \u003d 13 develops males, whereas when the cells are fused (6 + x) (6 + x) \u003d 14, gives females.

Gamets carrying different genital chromosomes is always formed equal to the number, this is determined by the mechanism of MEIOS. Paul giving gamets of the same type is called homogeneous. Paul giving two types of gamets is called heterogeneous. The splitting on it is reminded when analyzing crossing. In the other case, the splitting occurs in the ratio of 1: 1, as the statistics of splitting on the floor really corresponds to this:

Man 51:49.

Horse: 52:48.

Dog: 56:44.

Donkey, Sheep: 49:51

Mouse, duck: 50:50

The hereditary grip with the floor is the inheritance of signs that control the genes localized in the genital chromosomes.

In 1916, the first mutation of Drozdofilov was discovered - white eyes.

The inheritance of this attribute detected in regular crossings was detected dependency.

The attention is drawn to the fact that:

receptor crossing gives a different result, i.e. It has the value of crossing direction.

In F1, white-eyed only males, that is, a sign of adhesion with a certain floor.

the sign is distributed crosswise, i.e. From mother - son, from father - daughter.

The only recessive allele, not homozygot and not heterosigot. This condition is called hemisotia. The sign is determined by the only recessive allele.

Since the distribution of signs clearly repeats the distribution by the H-chromosomes, it can be concluded that the genes are physically localized in chromosomes, they are part of them.

A number of recessive signs, long-formation, hemophilia, missing γ-globulins in the blood are inherited. The dominant joined the flap is inherited by the lack of organic phosphorus in the blood, the darkening gene of the enamel of the teeth.

Hereditary grip with y-chromosome, from father to son. Signs of Syndactilia, Heperitrichoz Body.

Inheritance for female heterogeneity.

This type of inheritance is noted at chickens, butterflies and some fish. Pen painting in chickens, gene painted generated with floor.

P w: XY X M: XX

Striped black

Plymutrop Australp

F 1 m: xx w: XY

Striped black

P w: XY X M: XX

chern striped

F 1 w: XX M: XY

Striped striped

Reciprocal crossing gives different result

Inheritance CISS-Cross

Recessive gene appears in hemizigote

Symptoms bounded by the floor, which manifest only in one sex due to the analytical structure, although the genes controlling the sign are available in both sexes, for example, bold cows, egg production of chickens, etc.

Signs dependent on gender, for example, the development of rogues in sheep. Heterozygous beans (HH) horns, i.e. They are hornedness dominant, and heterozygous sheep (HH) ruffes, i.e. The horns of refcer. According to this principle, many secondary sexual signs are inherited.

8. Ground adhesion. Clutch groups. Genetic analysis of the adhesion of genes. Clutch and crossover in Morgan's experiments with drosophila.

The number of chromosomes in different species is small compared to the number of genes. Drosophila has more than a thousand genes for 4 pairs of chromosomes. If the genes are in chromosomes, each of them should carry a whole group of genes. These genes combined in one chromosome cannot comply with the rule of independent inheritance. Morgan showed that the genes in the same chromosome form a single clutch group.

A dihybrid crossing was delivered on Drozophile, in which the inheritance of the following features was studied:

P gray body x black body

stuff kr. Norm Kr.

F1 1) Gray Body 2) Black Body

norm. Wings are stuffed. kr.

3) Gray Body 4) Black Body

conceived. kr. Norm. kr.

Analyzing crossing showed that the hybrid forms only two types of hamets in which the combination of genes has not changed and remains the same as parental individuals. Such inheritance was called Captured.

Analyzing crossing is delivered in two directions. For reverse crossing from the hybrids, a female hybrid has been selected and crossed with males - line of the analyzer.

In the crossing, a mix of fetotypic class appeared, which indicates the formation of 4 classes of heams from a hybrid female. But instead of the equality of classes, as in the dihybrid crossing, descendants appeared with combinations of signs, characteristic of parental forms - 83%, i.e. The adhesion of genes is observed, in 17% of cases.

Morgan suggested that the grip violation of genes or recombination occurred due to the crossroads - crossinchiera In hybrid females. The males drosophila and females of the silkworm of the crosslinker are not, they have absolute grip of genes.

Gamets with chromosomes, which have thrown overcrowders, are called crossover, individuals with new combinations of signs that have arisen in the residues of crossover gaming - crossovers or recombinants. Scrossing classes are the result of a mutual exchange of chromosome participants, so they always arise pairwise and numerical equal. The crosslinker frequency is defined as the ratio of the number of crossovers to the total number of descendants in the crossing analyzing and is expressed as a percentage. 1% of the crossroads is a unit of distances between the goves and are called morgame. This frequency is different. The combination of genes constantly. This suggests that the genes occupy a permanent place in the chromosome, the location of the genes in the chromosome linearly, the crosslinker frequency reflects the distance between the genes: the closer the genes in the chromosome are located, the less the probability of cross hrometer (above the force of the adhesion of genes). The further the genes are from each other, the most likely the crosslinker (less clutch power).

9. Polyploidy. Autopoliploidia, its phenotypic effects and genetics. Amphidiploidia as a fur-zm of obtaining prolific allopoliploid. The value of polyploidy in the evolution and selection of plants.

Genomic mutations are mutations affecting the number of chromosomes, changing the genome-shaped set of chromosomes with localizes in them. These include aneuploidy and Polyploidy.

Polyploidy- This is a change in the number chromosome, a multiple of haploid.

Multiplying the same haploid number chromosome (genome) Naz-Sm autopoliploida. (AAA, AAAA, etc.) Combining several different genomes in the hybridization of Naz-Sm allopoliploidia (AAV, AAVR, ABB, etc.) differ polyployidium of the balance of the Balance, with an even number of sets of chromosomes, and unbalance-uu- with odd.

Polyploidy RKDKO is found in living, but the spread on the plants. The living polyploidy has a personnel of hermaphrodites. (Rainworm)

The appearance of polyploidy causes a number of events:

1) When chromosomes, chromosomes in the Masonry of Gameta may receive a complete somatic set of chromosomes;

2) polyploids may occur with spontaneous doubling chromosomes in somatic cells of the meristem. This leads to the emergence of tetraploid shoots, the flowers of which will produce diploid gametes.

Polyploydia can be caused artificially, exposing the plant with the action of B-B, affecting the formation of the separation of division.

Polyploid Polyploid Polyploid Polyploid Features:

Giantism (with a high degree of polyploidy is possible dwelcome);

Low Osmotic pressure.

Autopoliploidy.Har-Smiy Sterility Autopoliploid.

Genetics of autopoliploid Har-Xia 2nd main features:

The recovery of recessions is difficult;

The law of purity of Games is not as opposed to polyploids.

In natural populations, many polyptloids have a hybrid nature and anewing allopoliplodia. Arising amphianaploida (AB) Sterile and eliminate from the population.

Experimental The path of the origin of the fruitful amphidiploids

(Allotetraploid) was shown GD Kkarechenko. He managed to get a prolific hybrid between radish and cabbage.

10. The theory of mutations. Class-I Mut-th in Har-ru change of genotype. Number of mutations accounting methods (cIB, Meller-5).

Under mutation, the change in the hereditary material is understood. Mutational theory originated in 1901 - 1903, it was created by Gogo de Fris.

The main provisions: 1) mutations appear suddenly, jumps like discrete changes in signs. 2) The resulting mutation is stable and is inherited. 3) The process of mutation occurs - the process is non-directional. Alone and the same mutation may occur again, along with useful, harmful mutations arise. 4) Mutations are qualitative changes. They do not form continuous rows, are not grouped around the average.

Types. The basis for the classification of mutations can be laid different principles. In accordance with this, you can classify mutations in a different way.

Generative mutations They affect genes in the cells involved in reproduction, and therefore appear in the offspring, inheritance. The number of mutant cells of the mutant cells will depend on what stage of their formation the mutation arose. In the early appearance of it, for example, at the stage of mitosis preceding meyosis, a bundle of mutant cells may occur. If the mutation touched upon a cell at the final stage of its development, it will be single.

Somatic mutations The reason for the appearance of clones of genetically different-quality cells - mosaicism. In the organisms that breed sexually, the generative cells are early separately, somatic mutation can give a clone of cells with a mutant sign, which can be artificially propagated in vegetative way. In addition, mutation, affected cells of the meristem, of which escape with flowers is formed, can become a generative. Kinded mutation.

The clearer is the classification of mutations by the nature of the changes in the genotype. These are mutations nuclearaffecting the main array of genotype and mutation plasma, affecting cytoplasm organoid organoid genes (mitochondria, plasts).

Nuclear, depending on the scale of damage, divide on: geneThe changes affect the structure of individual genes (transition - replacement of one pyrine onto others. Purin or pyrimidine - on dr. pyrimidine; transversions - replacement of purine on pyrimidine or vice versa), chromosomal mutations or chromosomal restructuring affecting the structure of chromosomes ( Deletion Lost chromosome plot, Duplication One piece of chromosome is presented more than once, Inversion- B. One of the sections of the chromosome genes are located in the sequence, reverse compared to normal. If the chromosome section includes a centruller, inversion is called percentric, if this section inside the shoulder does not affect the centruller - paracentric, Translocation- Exchange of sections with non-homologous chromosomes), genomic Mutations that change the number of chromosomes (Changes expressing in aneeuploidy - a change in the number of XP-M, non-mental haploid, either in polyploidy-changing the number of XP-M, a multiple of haploid: outpolyploidide - an increase in the number of hrd sets and allopolyploidy HR-M in a sterile hybrid).

In 1927, Meller developed a fast and easy way to identify adhesive with a floor of death in the chromosome as a whole. For this method, a special line of drosophyl was created. Its feature is that the X chromosome contains two inversions. The first is very large, exciting most of the X-chromosome (SC 8), the second is smaller and is located inside the first. These two inversions lock the crosslinker. Females are homozygous. X-chromosome marked the same genome Apricot (W but) - Apricot eyes and yellow-yellow body.

Homozygous females cross with wild-type males, whose sperm is investigated for the presence of recessive lethal mutations. Daughters from such crossing have one chromosome molar-5 and one chromosome under study, each of the female F 1 is crosslinked individually in a separate test tube with the male F 1, which has a single X-chromosome type MELLEL-5. Reuses of wild-type males in F 2, testifies The fact that there is no recessive lethal mutation in the analyzed test tube. The absence of wild-type males in F 2 indicates that the studied chromosome contains at least one newly emerged mortar mutation. Meller showed that the frequency of the occurrence of mutations increases sharply during radiation by X-ray rays and the action of the iprite poisoning substance.

Meaning: In many cases, hrin and gene mutations are fatal. As a result, some. Khr's Mut-th ORD. The genes can turn together, and their common. The effect may result in the appearance of a "favorable" feature. Genid Mut. May lead to ariser-y in def. Locus of several alleles. This increases is the heterozygency of the population and its gene pool, and leads to an increase in intrapouch variability.

11. Methods of studying human genetics. Nonestly diseases, their distribution in the human population. Chromosomal diseases. Using biochemical methods for the diagnosis of hereditary diseases. Cell cultures.

The biological species of Homo Sapiens constitutes part of the biosphere and the predact of its evolution. SELECTLES TO REMEMBER THE LAWS OF HEATURED VARIABILITY. We have something other than the product of our genes. Human degree is a science of his heredity and variability. In a person's genetics, 3 main directions are distinguished:

the problem of genetic personality and its influence on the formation of a person's personality, the development of inconsistencies and abilities, the individuality of reactions to external influences.

the work of genes in the body in the process of individual development and livelihoods.

genetics of hereditary diseases adjacent to the Medicine genetics.

Methods for studying human genetics.

1. Method of pedigree or genealogical.

Galton introduced in genetics Analysis of the Pegoslocky, offered the method of their recording and received interesting results; When analyzing the pedigrees used statistical methods.

Next, Galton and his student Pearson developed this direction and created a biometric genetics. Analysis of pedigree allows you to set the type of inheritance of a person in a person. In the dependence on inheritance, the pedigrees have a different appearance of dominant autosomal inheritance, the sign is a dominant autosomal inheritance, and the sign is a phenotypically From the floor. Explorer, with recessive inheritance, differ in the fact that the sign may be absent in several generations, and its manifestation is accompanied by related marriages. Aid 3 degrees of relationship:

parents-children, sisters brothers. 50% of general genes.

uncle, aunt-nephews, nieces. 25% of general genes.

grass marriages. 12.5% \u200b\u200bof general genes.

The pedigrees with a recessive inheritance adherent with the floor, characterize with the well-traceable cry scross inheritance, and the fact that the sign manifests itself in men.

2. Twins method,

It showed that the twin samples are statistically acceptable, it made it possible to study the genetics of normal variability.

developed a reliable method for diagnosing twins using a large number of criteria.

he offered to explore both monosigitious and dialing pairs of doubtnets, having in mind that the Republic of Belarus is born at the same time and develop in the same conditions ..

All properties of the body are determined by the interaction of 2 factors - genotype and medium. Extending OR and RB, it is possible to identify the influence of the genotype and environment on the development of signs. We are compared for a number of signs in a large sample. On the basis of the data obtained calculates the indicators of the condancence (similarity frequency) and discordability. (Difference frequency). These indicators can be used to assess the importance of the genetic component with a given disease. Also allow you to establish under what conditions one or another is manifested.

The frequency of the twins is different in different populations.

3. Cytological method

At the heart of the human chromosoma, and the analysis of deviations from it. According to the Denver classification, all human chromosomes are divided into 2 unequal groups: 22 pairs of autosomes and 1 group heterochromosomes, including sex chromosomes (XX, Hu). In Medezos and Genetics, new The concept of chromosomal diseases, the cause of which is a violation of the number and structure of chromosomes. The mehanism of this phenomenon is a violation of MEIOS, which to express in the unresponsibility of chromosomes. It is to lead to trisomy and monosomy of the zygota Chemicals, alcohol, environmental pollution.

There are 3 types of chromosomal disorders in humans who are related:

with an excess of genetic material (OlImomy, polyploidy, duplication, triploidy).

with a loss of a part of genetic material (nylisomy, monosomy, deletion).

with restructuring chromosomes (translocation).

The disorders associated with the excess of chromosomal material are possible both in the autosoma system and in the system of sex chromosomes. In the system of sex chromosomes, trisomy is known in the X-chromosome (Triplo-X syndrome), the Kleinfelter syndrome with various options.

Trisomy in the X chromosome in women causes mental backwardness (easy oligophrenia), violation of the Gonad function.

Syndrome KLAINFELTER exists in several variants that differ in the genome of excessive and y-chromosomes. Recent options 2-4x + 1U, 1x + 2-3u, 2x + 2y. Symptoms on the female type, full sterility, mental retardation.

Diagnostics analysis of karyotype + on the Barra Tales.

Frequent chromosomal Daun syndrome or trisomy on 21 chromosome.

Characteristics: Clearly defined diagnostic signs; the frequency of the syndrome is increasing with the age of mothers, men are fruitless, the life expectancy is reduced, the risk of death from leukemia is 20 times.

Trisomy on the chromosome of the group d (13-15) or Pataau syndrome and trisomy on the chromosome of the group E (16-18), Edward syndrome meets less often. These chromosomal anomalies cause heavy and complex defects, the life expectancy of babies to calculate several mestes.

Syndrome Shershevsky-Turner Monosomy in X-chromosome (x0). The cost of growth, sexual development, underdevelopment of internal organs, vices of the cardiovascular and musculoskeletal system, small growth, a kind of head planting (sphinx head) and the wonderful folds on the neck.

4. Biochemical method.

gene study

at the level of cellular structures

Inheritance metabolic diseases are diagnosed.

For research, short-acting cell cultures are used, these are cultures of lymphocytes, as well as long-range-cultures of fibroblasts.

Prenatal diagnostics - uses the method of analysis of chromosomes, and biochemical. For this, the amniocentesis and the chorion biopsy. Amniotic fluid is exposed to an amniotic fluid, the sample of which is taken if the abdominal wall is taken on the 14-16 week of pregnancy. Top of the centrifugation is separated by living cells and cultivated. Child and the degree of risk for lubricated with the sickness.

Chorion's biopsy when taken to explore the exterior germinal shell ving for the 8-10 week of pregnancy. It places without cultivating cells to establish biochemical and chromosomal disorders.

5. The population method.

The answer to the question of how Mendel's laws are being implemented at the level of populations, as influenced by its factors such as mutations, selection, migration, gene drift. It is necessary to understand the epidemiology of hereditary diseases, planning activities that may prevent adverse effects on the genetic The device of a person. Investigations can be divided into 2 groups:

1-descriptions of populations and their genetic composition

2 analysis of the causes of the change of the gene pool.

12. The problem of living on earth. Development of ideas about originlife. The main stages of the chemical and biol of evolution.

This problemis 1 of the central problems of natural science. You can highlight a few approaches to the concept of "life":

substrate - life is determined through the structure of the substrate (proteins, nucleic acids and phosphorus - organic compounds)

functional - through the functional manifestations, open-reproducing system

substra-function approach - living organisms are open self-organized and self-reproducing systems consisting of proteins, nuclei acids and phosphorodorganic connections.

Development of ideas about the occurrence and life:

1) Costeconistic pre-I - about the deities, the creation of the world (all living things created God, then there was their evolving (so considered scientists of that time).

spontaneous, the birth of life - was distributed in China, Egypt, Babylon. Alternative to Corosoneism. Received In the 16th century Fish - from El, Mice - from the dirt (Paracels, Copernicus, Goethe).

parisermia hypothesis - ideas about the possibility of transferring life in outer space with 1 cosmic body to another. Life originated from space. Envelopes of ordinary organisms hit the ground along with dust and meteorites. Supporters - Louis Pasteur, Richard.

4) Early. Live of non-living. Life originated on the basis of common laws of nature. There was a not a large material system with a large density and a huge temperature consisted of particles quarks and leptons. The system broke out due to the violation of gravitats. Sustainability, an explosion occurred and 15-20 billion L.N.-beginning of the universe. In a distance Earth arises and in the cut chemical. Evolution arises life. Such is also that the earth has a cold origin (Otto Schmidt). The Earth was formed from the protoplanetic cloud with low temperatures. This cloud consisted of gas, dust and many particles.

5) Buddhist version - life was created by the world mind. This approach has not satisfy.

SL-IMAGE OF LIFE:

1) the presence is defined. Chem. Elements - 21 elements, the most important C, 02, S, P, N, N. In the residences of the Himst Evolution of the Obro-Soin 4+. It possesses unices, bonds: forms a compilation with conjugate bonds (1 and \u003d 2 connections). This leads to increased stability of the comprehensive and chemical. Act

Availability external. sources E.(UV, electr. Discharges, heat, radioactive radiation).

Lack of free. 02. The synthesis processes prevail, and not the collapse of the Org mol.

4) withdrawal of synthesis compounds from the synthesis zone, because At the stage of abiogen synthesis, the role of non-equilibrium pr-owls is manifested.

The emergence of self-organization-SIA systems. There were coacut drops with an unequal. Internal structure, they possess the setting in-c. Not certain proteins were subjected to the prebel, but the protobedts (the first living Org-we). The first self-deeds-mii were microspheres with D \u003d 2 MK. Inside were proteinoids. Engeyn - the first were hypercycles. From them - hypercycles of the 2nd order. According to Engeyn, the prebaux. The selection among the hypercycles led to their improvement - in the cuts of m. The first source is arising. Systems.

The emergence of the gene. Code and appeared Lipidmembrane-X p.

the emergence of coenzymes

Life ariser:the first living Org-we were heterotrophs. Life of susta in the form of simple multi-axis systems with food chains. The first org-we have arisen in the form of SUCH individuals in the primacy. Biogeocenosis. The most ancient Org-we were in Archey (3.8-4 billion years ago) - prokaryotes. They are situated in a medium using ready-made org. In Va, the cat in the ocean was becoming less. At that time, the appearance of the first carotrophes. They were able to synthesize the Org in Wa from Neorg, the energy of chemical bonds or solar (the background d / the occurrence of chemo- and f / synthesis). First f / synthetics. About 3.5 billion L.N. Their predecessors are anaerob, Bakt. They formed stromatolites (layered limestorms in the form of columns from the remnants of the Bakt-th and blinque algae). In the atmosphere there was an increase in 02, it led to the occupation of Eukarotov. The first eukaryotes arose 1.5 million liters. n. Have become numerous, about 1 million L.N. Simples, anaerob, eukaryota - Zhuktica Rast. And Water-Lee. There were ordinary and complex many org. Primitive ras and alive appeared 650 million L.N. Modern alive is raised in Cenozoa (65 million L.N.). Further Owl-I led to a person. In the present, the time is distinguished 3 N / kingdoms: archeobachat, eubacht and eukaryotes.

Archaeobakt. live in Ile, in volcoloch. Sources. They prevailed in the early stages of the development of life on Earth. Were the first prokaryotm. Because Eukarotov: SUB-T 2 hypotheses - invagination and symbiotic me. Invagination: The CL compute had a double membrane, could the shape of the patch and the capture of DR CL occurred. Symbiota: A few types of heterotrof appeared from the primitive CL. and autotrophic. CL, with their association a new organism has arisen. Those. Chloroplasts were f / synth bacteria, and mitochondria- heterotrof. anaerobe. Bacteria.

The main stages of biopoede (chemical. And biol. Evolution):

1) Biol formation. Monomers. The atmosphere of the Earth was at first wearing the Exta Har-r. There was no free. 02, but there were pairs of H20, CH4, NH3, CO and C02. In du-teh. Reactions are Whether Org-E Seda: Nson, Nson, and others. These compounds come into reactions to each other. Biopolymers arise - a / k and nucleotides. Those. Synthesis Org. The compounds were in the early stages of the evolution of the solar. Systems. A / k, porphyria, pyrimidine, Purin was found in meteorites. The monomers combined with each other by phosphoric ties.

2) the formation of polymers, i.e. The formation of essential connections. There was a mix of simple substances in polysaccharides, peptides, etc. They were concentrated in the waters of the primary ocean.

3) OBR-E source of systems, i.e. There were protobedts. Oparin suggested that this is a coacantic drops of genes controlling morphogenesis. East. The role is gene movable retroviolet-like elements can cause large mutations.

13. Genetic theory of natural selection. Object, sphere, action and selection mechanism, its quantitative characteristics. Factors affecting the selection efficiency.

The natural selection is the most important driving factor of evolution, which determines the directional change in the composition of the population, i.e. To adapt them to environmental conditions. Darwin emphasized that the natural selection-selection occurring in nature without human intervention. This is preserving and preferential reproduction. Experiencing the most adapted. The selection occurs as a result of the struggle for existence through elimination, therefore the phenotypes are selected. Compete live organisms. The selection goes through the phenotypes, but genotypes are selected. Moreover, non-individual genes are selected, but holistic genotypes that determine the ontogenesis of the next generation.

Newly emerging mutations reduce fitness. The selection goes on combinative variability - the main material for selection. Phenotypic expression of mutations, i.e. The degree and nature of the cause of the body depends on the genotype and on the conditions of the medium in which this genotype is implemented. Mutational variability is not directed, but the combinative variability can be considered random only if there are pamctions, i.e. Accidentally crossing individuals of this generation. However, since individuals are multiplied only sufficiently adapted and this comes from generation to generation, in a series of generations combination-directional process, even in the case of pamctions.

A complex hierarchical system of intraspecific groups is optimal for evolution, because It provides the rapid detection of new alleles, the rapid distribution of adaptive options and a high level of variability. The evolutionary process is influenced by the effect of population fluctuations: with an increase in the number, a large number of combinations are implemented, which ensures an increased genetic diversity of the population. In decline in the number, adverse options are eliminated and homozygosity is increasing.

Natural selection-process directional, vectorized and as any vector has 3 parameters: application point, i.e. The sign that is selected; the amount characterizing adaptive value, or relative adaptability; the direction determined by the condition for the struggle for existence.

15. View as stage and result of evolution. Definition concept. View of prokaryotm and eukaryot. Politic and monotypic species.

The concept is based on: systematics, genetics, eV. theory.

Eidology - science research. views. The form - (logical meaning) is an expression of similarity in a number of single parameters. Many concepts of understanding of the species were created in history.

The first Aristotle is a group of similar organisms. J. Rhine is the minor set of organisms that reproduce themselves like. Linnes - as a system category for classification (the main criterion - morphological similarity), was proposed to compare the individual with museum specimens - a typological concept. There was a nominilistic concept - forks abstract. Politiciza concept - in. consists of 2 and more subspecies. Monotypic - does not share on subspecies. Tinkokofka Penochka - European, Siberian, Altai. Modern - Biological concept - (Mayre, Dorzhansky, Zavadsky, Timofeev-Resovsky).

reproductive unit -T.E. The individuals of this species are crossped by M \\ in itself and reproducely isolated from representatives of other species.

environmental unit - every kind of them. your eq. Niche population of one environmentally replaceable.

genetic unit-im. total. Agenophobe, in which every individual them. Small. Plot.

View- This is a group of actually (or potentially) crossing populations reproductively isolated from populations of other species. The basis is the ability to cross-country.

But it is not applicable for individuals with dust reproduction for paleontological.

ViewrEALEN T.K. It comes from the original population, which has a gene pool inherited from ancestors and which determines further development, they are environmentally replaceable, i.e. Have a common environmental niche.

Criteria of type - This is a combination of certain signs, a cat. Allowed to determine the form, separate it from other species - which determines the place of species in the general system of Ogan. World.

Maintenancecriteria . Morphological - similarity of the external and internal structure of individuals. (But sexual deformation, types of twins (they are externally similar, but genetically insulated is not cross it) Polevka is ordinary 1V.-5P \\ c.

Genetic -the view is a genetically closed system. They do not cross Dr. with Dr.

Ecological - its own ecla. Niche (alive. space and food resources.) It can be potential and real.

Geographical - It occupies a certain area - the historically established area of \u200b\u200bthe printer., where the species is found throughout the whole life. It can be solid, desicive (torn) depending on the size of the range - cosmopolitans, endemics, relict, replacing.

Physiological- The similarity of the processes of the vital activity of individuals 1 is the cause of reproductive isolation.

Additional:

1) Coriological - structure and number of chromosomes.,

2) B \\ x - the difference in the composition of alcoholoid proteins, glycosides.

3) Criterion of nucleotide specifics - the ratio of T + C to A + T determine the coefficient.

4) molecular hybridization - allocate DNA in two types. Spread and 1 chalk. Cool and look like the formation of duplexes (speed).

5) Immunological - on the reaction of the formation of precipitate, judge about the relationship of species.

6) Ethological - similarity of behavioral reaction .

7) palinologic - analysis of the dispute, pollen grains.

8) Albumin index - serum blood protein in which groups of organisms are very different.

9) Heat resistance of cells and fabrics (voles). But in order to describe the view you need an integrated approach.

Structure of type. The question of the structural unit is not resolved, since it is difficult and many transitional forms.

Semi-love- Environmental or geographic race Almost achievable position of an independent species. This is a group of individuals inside the species, which is almost isolated from other individuals. Crossing almost does not occur.

Subspecies The group of morphologically similar individuals occupying a certain part of the species range and phenotypically differs from other such groups. - Outwardly. Diagnostic features, - occupy disunity of aroles, are part of larger structural formations. Ordinary fox - 20 subspecies.

Environmental Race - Ecotype - a group of individuals, which is well adapted to local conditions of existence. (ant - Forest, Olugova, in plants to the south. and sowing slopes).

Population A group of individuals is united by the unity of vital activity within the population.

In animals inside the population - race, tribe, abberation. - Easy, on a morphologist. and physiologist.

The more structured the view, more evolutionarily beneficial. And this indicates a speciation.

View - A group of individuals similar to morph. And genetic features occupying a certain range, and capable of engaging dr. With dr.

But for agamo species - AGAMOS - Cleanchable, species breeding without fertilization, - parthenogenetic - Parthenos - Muffs - Women's genital cell develops without fertilization, - Self-opalizing. – for them, see - a group of phenotypically similar individuals with a nearby genotype, and the associated community of evolutionary fate - there is no genetic combinatorics.

Type of contradictory concept as the stage of the evolutionary process, for it, it is impossible to allocate all the criteria, some blurred or as a result of evolution - All criteria are very bright.

16. The speciation is a source of diversity in wildlife. Mechanisms of allopatric and sympathy species.

Recruitment - percent. There are one or several new species from the species, we souche earlier.

The speciation is the main stage of the evolutionary process. When forming new species - the transition of quantitative changes to high-quality. There are gradual and instantaneous. Gradual divide on allopatric and symplicity.

A necessary condition for any speciation is reproductive isolation. The value - it contributes to the differentiation of forms and their devices to different conditions of the medium.

Allopatrical - Education of new types based on spatial isolation. He opened Wagner. In the 20th G.G. contributed to Zavadsky, Mayer, Clausen,

Populations fall into different environmental conditions. Due to the differentiation and insulation, one evolving group disintegrates on 2 or more evolving units. There is no full reproductive isolation between populations. The populations become so genetically different, which lose the ability to crossbing. New species are formed.

It can occur in two ways:

1) When the initial type range is expanding. In the population resettlement, adapt to new conditions.

2) New species may occur by fragmentation (disintegration of the parental range). The population is so isolated that gene sharing is impossible.

Adaptation to the new Sl-M and the humble drift of the genes in a slightly. Pops lead to changes in the frequency of alleles and genotypes. In the cuts of the long-term disassemble, the Pop M-M-Nimi may occur genetic. Isolation, preserving even if they are again prone together.

Example: May Lily.

Not always only insulation leads to the speciation. We still need conditions:

1) Elimination of a gene flow, as a result of what differences between populations of the species.

2) The change rate of the medium does not exceed the speed of compensatory adaptations.

3) New environmental conditions should be maintained for a long time.

Sympric. The new look occurs within the original area area. Need-Mo Development K.L. Fur Ma Reproductive Isol-Ai. The following methods are known.

1) the emergence of new species by changing the karyotype, for example, during autopoliploidia. There are groups of close species with multiple chromosome numbers. Chrysanthemums have the number of multiple 9, 18, 27, etc. The processes of polyptloidization are reproduced by the delay in the discrepancy of chromosomes in MEIZE. Polyptloids may occur in nature. The emerged polyploid individuals can give viable offspring only when crossing with individuals carrying the same number chromosomes.

During the few generations, if polyploids pass "control" of natural selection and turn out to be better than the original diploid, they can spread and coexist with jointly breeding views, or, more often, just displace it.

Among the animals, polyploidy plays a smaller role in the speciation.

2) by hybridization, followed by doubling the number of chromosomes - allopoliploidy.

3) seasonal isolation. Terms of color I am arrival at different. time. Pinus Radiata blooms in February, and P.attenuata - in April.

4) Ecological isol-me. Two kinds, whit-e in the same region, is pretty different. Usl-I will do. Viola Arvensis grows on lime soils, and v.tricolor - on sour.

5) mechanical. Isol-me. Blind-naughty species of growing experienced different. animals.

6) non-visual hybrids, the sterility of the Gibb-in F1, the inferiority of the flexible f2.

Features of symplic speciation - the emergence of new species, morphologically close to the original.

50% of plants - allopolyploids (Cultural plum 2n \u003d 48 originated by hybridization of the turn 2n \u003d 32 with alcho 2n \u003d 16).

18. Basic forms of natural selection. Examples and results of their action. The role of selection in evolution.

SMALGAUZEN made a contribution to the development put forward ideas about stabilizing and driving selection. More dseructed, destabilizing, frequency-dependent, K- and R -OTbor.

1. Stabilizing - if the conditions of the medium are relatively constant contributes to the elimination of individuals with deviations from the mean value of the feature and properties, i.e. which will noticeably deviate from the norm.

A) normalizing - leads to elimination of evades from the norms. The result is the creation of a well-known functioning genome. Stub.Ob. Empty - poorly adaptive gene. Options to external factors. - genes, options that are characterized by a decrease in fertility.

Example: The established dimensions and shapes in flowers in insectopable plants, they correspond to the structure and shape of the body of the insect - pollinator.

B) Canalizing - means the survival of organisms with a more stable mechanism of ontogenesis. As a result, the processes of the development of the body are stabilized. Fish, gutteria, gingo preserved. This constancy of Gensley called - persistence - that is, the evolution is unchanged. With the autorevoor development, mutations accumulate. They persist in heterozygous state, the topics create a mobilization fund of variability. So It occurs - autonomization is a smaller dependence of development from external factors. Pr: Photoperiodism of plants - respond to changes in photoperiod, no factors - no.

2. Driving - manifests itself in naturally changing conditions. The environment is preserved by individuals with deviations from the average value only in one direction, not favorable for the sub-standard submitters.

A) directed - acts when there is a slow change in the medium and there is a gradual population conversion. Or with quick and goes faster. Pr: The emergence of insect resistance to pesticides. They have resistance. Mechanisms are unequal. In some cases, it is determined by the dominant genome., In others - recessive. Prior: Immunity production to the oysters virus. As a result, 10% of the population remains. However, gradually the number began to recover. And for 25 years it became more initial. Standing persistent individuals.

B) Transitive - the action can be traced as an example of studying industrial melanism. The bright coloring of butterflies made them imperceptible at the trunks of the trees. After blackout and they gradually became dark color, because Lightly exterminated predators. In conditions of pollution, light and dark forms have been released, preferably the dark forms will turn out. It turned out that they differ genetically.

The difference from the directional - starts from the source forms.

3. Diastructive - bursting - favors the preservation of individuals with an extreme expression of signs and eliminates intermediate forms. Pr: Oceanic islands and the presence of insects on them or with strong either without wings.

4. destabilizing - aimed at increased variability. In different environments.

5. Frequently dependent - depends on the frequency of occurrence of genes. In favor of rare genotypes. Pr: The ratio of simulators and insect models. The more imitators, the selection is more ineffective. Migrants get an advantage when crossing as representatives of rare genotypes.

6. K- and R- there are two approach to reproduction of species. Having producing a large number of eggs. We spend little energy in the body. And vice versa. K- and R - strategy. It is favored by a slower ravitia, greater competitiveness, late breeding, larger body sizes, not a large number of descendants.

R is favored by rapid development, the maximum increase in population, early breeding, small body sizes, great chilo of small descendants.

R is a larger number of individuals, the ability is more efficient. Using environment resources.

In nature, they manifest themselves together. Pr: Tropical ants First R- strategy - the seizure of new territories, colonization, after saturation of the area, the selection direction changes. Exacerbates inside the species competition. And the k-selection is valid (Oyster - 500 million per year, chimpanzees - 1 children at 5).

7. Sexual - concerns signs of individuals of one sex. The result of the device, which ensures the success of individuals in leaving after the offspring. Pr: Bright coloring husband. (instrument of tournament fight, etc.)

The role of natural selection. Selection pressure can lead to certain results only within the framework of defining physical and chemical laws. The nature of animals is inflicted is ultimately limited by the fundamental properties of those elements and molecules of which they consist. 1 - supporting. - A certain level of fitness, allowing it to exist in these conditions. 2 - accumulating - the selection retains evasion increases adaptability. They accumulate in the population. The phenotypic expression of signs is enhanced. The selection on this feature operates in one direction, the sign is enhanced. 3 - a creative role is manifested - changes the phenotypic expression of mutation, creates gene complexes that ensure the adaptability of the following generations;

promotes the formation of new species;

there is a process of device tool to the conditions of the OCC. Cf. and joint existence with other organisms; - to the autonomization of development from external factors; - To progressive evolution, determining the rate of evolutionary transformations.

It is a self-regulating process. Analogy with automatically adjustable device. Controller, object, direct and feedback channels. As a regulator, an external environment (biogeocenosis), a controlled object - population, direct communication - to the population, reverse - from the population to biogeocenosis.

Scheme of self-regulation

19. Isolation as one of the factors of evolution. Geographic isolation. Biological isolation carried out by pre- and postzyigotic mechanisms. The role of isolation in the speciation.

Insulation is a necessary factor. The process of speciation is impossible.

2. Biological. Precision The mechanism is to meet with animals, and the Gametophytes in plants are 4 forms.

2) Seasonal, 3) behavioral, 4) mechanical.

1) Biotopic. - at the place of habitat, i.e. See species in 1 geographical area, but occupies different biotopes. Pr: In Naz.am. - 3rd. Oak (sandy, lime, magmatic).

2) Seasonal - when the view dwells in the 1st geographic area, but differs in the time of reproduction. Pr: c. Drozofil. - Rimnize the day and night.

3) Behantic - different types of animals have features, the cat does not allow in reproduction with representatives of another species. There may be different mechanisms, - visual, - rumor, they blame, - tang away.

Pr: AM. Svetlyk - Site - light signals (from different species - yellow, green. Golubs.)

4) Mechanical - the difference in the size and morphology of the genital organs and in animals and in plants (flowers under certain insects).

Postzyigotic1) The death of Games - the insemination is there, but the egg is not fertilized.

2) The death of the zygota is fertilization, but it dies due to the immunological incompatibility of hemes, tissues.

3) The death of hybrids is not viable organism. 4) the formation of stylish descendants.

Each type is a genetic system during evolution. More efficient preydic mechanisms. Factors that enhance the genetic difference between the species, i.e. Each type is separated from other species.

Insulation is non-directional and stacking.

20. Draif of genes and population waves as evolution factors, their role.

Gene drift is a change in the frequency of genes and genotypes in small populations occurring under the action of random factors. The phenomenon is open to Siulm Wright and Ronald Fisher, in Russia - Dubinin and Romasim. The occurrence of genotypes in the population depends on the 4 factors.

number of population

Wright found that in a small population of the gene drift is very effective. It prevails over the action of the selection - the selection prevails in a large population.

mutation pressure

High mutational pressure (high frequency of mutations) prevents the action of gene drift.

thread genes

To effectively effect the gene drift, it is necessary that the population is isolated from neighboring populations. Even a small flow of genes weakens the action of the gene drift.

selective value of allelel

The higher the selective value of the allele, the higher its advantage during the selection, the lower the gene drift.

Thus, the gene drift is effective in the case

if the population is represented by small insulated colonies;

if the population is large, but divided into small groups of micropopulations, the cat is also isolated from each other

if the population is large, but periodically its number falls sharply and the population appears again at the 1st stage of its formation passing through "" narrow neck "" low numbers (the effect "of the" bottle neck "). It has important principle of founder. He is open to Mayer. Example: There is a large population on a certain territory. Several individuals accidentally turn out to be isolated (enters the island). If the conditions in a new place are favorable for life - these animals form a new population and the genetic features of this population will largely be determined by the genetic properties of those animals, the cat was the founders of this population. The genuofund of the new population will differ from the gene pool of the parent population. The founding animals are not carriers of all that info and, the cat is in the parent population, the gene pool of their occasion and depleted, therefore, does not represent a representative sample of the material of the population. The properties of the new population are determined by the accident.

Results of the drift of genes

It may increase the genetic homogeneity of the population, that is, it increases its homozygosity;

The populations at the beginning of a similar genetic composition and dwelling in similar conditions may result in the action of the gene drift lose this property.

Contrary to natural selection in populations can be maintained by alleles, the cat reduces the fitness of individuals.

Thanks to population waves (change in population), there may be a quick and sharp increase in the frequency of rare alleles.

Population waves as an elementary evolution factor

Population waves - population fluctuations. They can be caused by different factors (biotic, abiotic). There may be observed both periodic and aperiodic oscillations of numbers. Waves of life - an elementary factor of evolution. When the population growth is balanced, its number fluctuates around some more or less permanent value. Often oscillations can be caused by seasonal (annual) changes (humidity, temperature, food).

Classification of population waves

1 type - Periodic fluctuations in numbers. Org, living in a short term. Har-but for insects, 1-year plants, most mushrooms and microorganisms. In animals and plants, seasonal fluctuations are not equally reflected in different age and genital groups in the population.

2 type - Aperiodic oscillations. They depend on the complex combination of a number of factors: from favorable for this type of relationship in food chains (weakening the press of predators for victims, an increase in feed resources for). Such oscillations are reflected in many types of alive and raise in these biogeocenosis. Example: cycle of fluctuations in locust. For many years they do not commit migrations, but with an increase in the population density, they appear wings and migration begins.

3 Type - Increase the number of populations in those areas where there are no enemies. Example: Flash of rabbits in Australia.

4 type - Rare non-periodic fluctuations in the number associated with natural disasters - the destruction of biogeocenoses or entire landscapes. Example: Several dry years may cause changes in the appearance of large areas (the occurrence of meadow vegetation on the swamp, burnout of peatlands).

All factors, the cat affect the number of populations is divided into:

independent of density (when there is no dependence on the magnitude of the population). This includes abiotic factors (harsh winter, storm, drought). They can lead to a sharp decrease in the number of different Org-Mov, which occurs regardless of their initial density. The factor driving a change does not experience influence from changing. abiotic.

density-dependent if their effect on the population is a function of density (food security. Intrusual competition). In some cases, biotic factors depend on the density straight. So, the higher the population's density, the stronger the action of the factor (Pr: the higher the density of the plants, the stronger they shade each other). As the population density increases, the mechanisms of self-regulation (decline in fertility, increase mortality, etc.) are involved. These mechanisms return a population to its original state. All these are internal regulators of numbers. They work automatically immediately as soon as the population size exceeds the threshold value. In the future, the decrease in the number leads to the fact that food reserves becomes more, therefore the fertility increases, the number is growing. Thus, a dynamic equilibrium is achieved in the population.

The fluctuation of the number in populations is stronger in relatively simple ecosystems, where few populations are included in the community.

The evolutionary value of population waves is a supplier of evolutionary material. The role in small populations is especially important. The action of population waves is statistical and non-directional.

21. OSN. For example, phylogenesis: Diviggen, convergence, parallelism and phyletic evolution.

1) Diviggen - The emergence of differences based on the 1st and the same organization. The races and the OBR-E two species from one, bidding. CX-V is explained by the relationship, and the difference is adjusted to the SL. medium. The reason is the races of different ecologist. niches and intergroup. Commier-I results in competition of two ecologists. Groups, in each of which the most distinguished by the most distinguished from another group. Fur-M is based on isolation, armor. Changes, popplots. Waves and natural selection.

On microevolution. The process level is reversible (2 populations are able to exist and exist as one). At the macro-level pr-with irreversible. A new look can not merge with the parent. There are types of divergence: 1) Dichotomic branching (two forms are formed), 2) Adaptive radiation (many forms). Divergence -OSN. Form of phylogenesis.

2) Flytic Ow. - gradual evolution. I change within the phylogenetic line, going in one direction. One species, gradually transforming, can give the beginning to another. So This is an evolution on the length of time without divergence.

3) convergence - phenomenon, counterpart. Divergence. The formation of similar signs in unrelated groups of Org-B. There is similar to the emergence of similar devices (in the same conditions of the environment in different organisms). CX-in body shape at sharks, dolphins, ichthyozaurus.

4) parallelism - Independent examples of similar prize-in kinship. Org-Mov groups. Similarity is explained by the relationship and adaptations to similar sleep; Differences are associated with the PRI of the divergence of parental org (sea cat, walrus, seal). Come to the similar body of the body and limbs. 2 types of parallelism:

• Synchronous - which occurs at the same time in different groups of Org-Mov (the evolution of 2 groups of mammals hoofs: extinct representatives of the Otr Liptapterns from South America and the ancestors of a modern horse 5-tall phenopodes).

• Asynchronous - independent development in a similar direction of phylogenetically close groups at different times (the development of saber 4 times in 2 independent branches).

The parallelism is a business-smiling for different groups on the physiologist., Ecologist, Biohim, signs. A parallel evolution is explained by the generality of the gene structure of the parent groups and changes. In close taxes, the variability (wheat ordinary and dwarf). If similar signs are rated on the basis of similar organs, it will lead to convergence if on the basis of homologous paralialism.

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Chromosome - nucleoprotein structures in the kernel of the eukaryotic cell (cells containing the kernel), which become easily visible in certain phases of the cell cycle (during mitosis or meiosis). Chromosomes are a high degree of chromatin condensation constantly present in the cellular core. The term was proposed for the designation of structures detected in eukaryotic cells, but in recent decades are increasingly talking about bacterial chromosomes. In chromosomes, most of the hereditary information is concentrated.

These types of chromosomes are distinguished: equal depreciation (meticenter), (centromer in the middle, and shoulders of equal length); Unexpose (sub present-centered), the center is shifted, not in the middle of the chromosome, the length of the shoulders is unequal; Chopkidoid (acrocentric), the center is shifted to one of the ends of the chromosome, one of the shoulders is very short.

Chromosome as a complex of genes is an evolutionary structure inherent in all individuals of this species. The location of the genes in the chromosome plays an important role in their functioning.

The change in the number of chromosomes in the karyotype (chromosomal set) of a person as a rule leads to various diseases. The most famous and common chromosomal disease in humans is a Down syndrome, the cause of which is trisomy (excess chromosome) in the 21st chromosome. They suffer from this disease 0.1-0.2% of humanity. Often because of the trisomy of 21 pairs of chromosomes die fruit, but sometimes people suffering from Down syndrome are waiting to old age, although in general and live less. Trisomy also known in the 13th and 18th pairs of chromosomes, "Patau and Edwards syndromes, respectively. People with such defects chromosomes die in the first months of life.

It is also quite often a person has a change in the number of genital chromosomes. Among them is a monosomy X (from a pair of chromosoma in humans there is only one (x0)) - this disease is called Sherezhevsky-Turner syndrome. Less often are trisomy X and clanfelter syndrome (xhu, xhhu, huu, etc.). The factors determining the male development type are in the U-chromosome, the female - in X. Unlike the mutations of somatic chromosomes, the vices of mental development in patients are less characteristic, within the normal range, and sometimes even above it. However, they often experience violations of genital organs, hormonal imbalance. Where more often are the defects of the development of other systems.

Chromosomes are an intensely colored caller consisting of a DNA molecule associated with giston proteins. Chromosomes are formed from chromatin at the beginning of cell division (in mitosis proofased), but it is better to study them in mitosis metaphase. When chromosomes are located in the plane of the equator and are clearly visible in the light microscope, the DNA in them reach maximum spiralization.

Chromosomes consist of 2 nursing chromatids (double DNA molecules) connected to each other in the primary hauling area - centromers. The centerier divides chromosomes by 2 shoulders. Depending on the location of the chromosome centrners are divided into:

metic centers are located in the middle of chromosome and shoulders are equal;

submetric center center is shifted from the middle of chromosomes and one shoulder shorter than the other;

acrocentric - centromer is located close to the end of the chromosome and one shoulder is much shorter than the other.

In some chromosomes there are secondary hats separating from the shoulder of the chromosome a plot called the satellite, from which nucleolo is formed in the interphase kernel.

Rules chromosomes

1. The constancy of the number.The somatic cells of the organism of each species have a strictly defined number of chromosomes (in person -46, in a cat - 38, in a flush-drosophila - 8, a dog -78. In chicken -78).

2. Parity. Each chromosome in somatic cells with the diploid set has the same homologous (identical) chromosome, identical in size, form, but unequal by origin: one - from the father, the other - from the mother.

3. Individuality.Each pair of chromosomes differs from another pair with dimensions, shape, alternating light and dark stripes.

4. Continuity.Before dividing the DNA cell doubles and the result is 2 nursing chromatids. After dividing into subsidiaries, it falls on one chromatide and, such about it, chromosome is continuous - chromosome is formed from chromosome.

All chromosome are divided into autosomes and sex chromosomes. Autosomes are all chromosomes in cells, with the exception of sex chromosomes, there are 22 pairs. Sex - this is the 23rd pair of chromosomes, determining the formation of a male and female organism.

In somatic cells there is a double (diploid) set of chromosomes, in the genital - haploid (single).

A certain set of chromosomes of a cell characterized by constancy of their number, size and shape, is called karyotype.

In order to understand the complex set of chromosomes, they are posted in pairs as they decrease their magnitude, taking into account the position of centromeres and the presence of secondary pulps. Such systematic karyotype is called an idiogram.

For the first time, such a systematization of chromosomes was proposed at the Congress of Genetics in Denver (USA, 1960)

In 1971, in Paris, they were classified chromosome on coloring and alternating dark and light hetero and eurobine bands.

To study the karyotype of genetics, the method of cytogenetic analysis is used, in which a number of hereditary diseases associated with a violation of the number and shape of chromosomes can be diagnosed.

1.2. Life cycle cells.

The life of the cell from the moment of occurrence as a result of division to its own division or death is called the life cycle of the cell. Throughout the life of the cells grow, differentiate and perform specific functions.

Life cells between divisions is called interfaz. Interphase consists of 3 periods: the pretenttical, synthetic and postsynthetic.

The pretentical period should be immediately followed. At this time, the cell grows intensively, increasing the amount of mitochondria and ribosomes.

The synthetic period occurs replication (doubling) the number of DNA, as well as the synthesis of RNA and proteins.

In the postsynemetical period, the cell is covered with energy, proteins of achromatin spins are synthesized, preparations for mitosis are prepared.

There are various types of cell division: amitosis, mitosis, meyosis.

Amitosis is a direct division of prokaryotic cells and some cells in humans.

Mitosis is an indirect cell division, during which chromosomes are formed from chromatin. The somatic cells of eukaryotic organisms are divided by mitosis, as a result of which the child cells receive exactly the same set of chromosomes, which a subsidiary had.

Mitosis

Mitosis consists of 4 phases:

Proofase - the initial phase of mitosis. At this time, the DNA spiral begins and shortening chromosomes, which from thin invisible chromatin yarns become short thick, visible in the light microscope, and are located in the form of a tangle. The nucleolo and a nuclear sheath disappears, and the kernel breaks down, the central cells of the cell center differ in the poles of the cell, the filaments are stretched between them.

Metafase - chromosomes are moving to the center, the threads of the spindle are attached to them. Chromosome are located in the equator plane. They are clearly visible in the microscope and each chromosome consists of 2 chromatids. In this phase, you can count the number of chromosomes in the cell.

Anphase - nursing chromatids (appeared in the synthetic period with DNA doubling) diverge to poles.

Buck Faza (Telos Greek - End) is the opposite of the Profase: chromosome from short thick visible becoming thin long invisible in the light microscope, a nuclear sheath and nucleolo are formed. Ends of telphase by the separation of the cytoplasm with the formation of two subsidiaries.

The biological value of mitosis is as follows:

daughter cells get the exact same set of chromosomes, which was at the maternal cell, therefore in all cells of the body (somatic) constant number of chromosomes is maintained.

all cells are divided, except for the floor:

there is an increase in the body in the embryonic and posthamsbrion periods;

all functionally obsolete cells of the body (skin epithelial cells, blood cells, cells of mucous membranes, etc.) are replaced by new;

regeneration processes (restoration) of lost tissues occur.

Mitosis scheme

Upon exposure to adverse conditions on the divided cell, the spindle division can unevenly stretch the chromosomes to the poles, and then new cells with different set of chromosomes are formed, the pathology of somatic cells (outosome heteroploidide) occurs, which leads to diseases of the tissues, organs, organism.

Chromosome are nucleoprotein structures of eukaryotic cells, in which most of the hereditary information is stored. Due to its ability to self-reproduction, it is chromosome that provide a genetic connection of generations. Chromosomes are formed from a long DNA molecule, which contains a linear group of multiple genes, and all genetic information be about a person, animal, plant, or any other living creature.

The morphology of chromosomes is associated with the level of their spiralization. So, when the chromosome interphase stage is maximally deployed, then with the beginning of chromosome division, they are actively spiralized and shortening. They achieve their maximum shortening and spiralization during the metaphase stage when new structures are forming. This phase is most convenient to study the properties of chromosomes, their morphological characteristics.

History of opening chromosomes

In the middle of the XIX century in the middle of the XIX century, many biologists studying in the structure of plants and animal cells, drew attention to thin threads and the smallest ring-shaped structures in the kernel of some cells. And now the German scientist Walter Fleming applies aniline dyes to treat nuclear cell structures, which is called "officially" opens chromosomes. More precisely, the detected substance was called "chromatid" for its ability to stain, and the term "chromosomes" in everyday life (in 1888) introduced another German scientist - Heinrich Wilder. The word "chromosome" comes from the Greek words "Chroma" - painting and "Somo" - body.

Chromosomal theory of hereditary

Of course, the history of study by chromosomes did not end in their opening, so in 1901-1902, American scientists Wilson and Saton, and independently of each other, drew attention to the similarities in the behavior of chromosome and Mendeleev's heredity factors - genes. As a result, scientists came to the conclusion that the genes are in chromosomes and precisely through them from generation to generation, genetic information is transferred from parents to children.

In 1915-1920, the participation of chromosomes in the transfer of genes was proven in practice in a whole series of experiences made by American scholars and employees of his laboratory. They managed to localize in chromosomes of flies-drosophila several hundred hereditary genes and create genetic maps of chromosomes. Based on this data, a chromosomal theory of heredity was created.

Building chromosomes

The structure of chromosomes will be varied depending on the type, so the metaphase chromosome (formed in the metaphase stage during cell division) consists of two longitudinal threads - chromatide, which are connected at the point of the centromer. Centrome is a section of chromosome, which is responsible for the discrepancy between nursing chromatids in subsidiaries. She divides chromosoma into two parts, called short and long shoulders, it is also responsible for dividing chromosome, since it contains a special substance - the kinetchor, to which the structures of the separation of division are attached.

Here in the picture shows the visual structure of the chromosome: 1. Chromatids, 2. centromer, 3. Short shoulder chromatid, 4. Long shoulder chromatide. At the ends, the chromatids are televomers, special elements that protect chromosomes from damage and prevent the sticking of fragments.

Forms and types of chromosomes

The size of chromosomes of plants and animals differ significantly: from the fraction of the micron to tens of microns. The average length of the metaphase chromosome of a person is in the range from 1.5 to 10 microns. Depending on the type of chromosome, its ability to stain is different. Depending on the location, the centrners distinguish such forms with chromosomes:

• Metic-centered chromosomes for which the middle arrangement of centromeds is characteristic.
• Sublesstrical, for them is characterized by an uneven arrangement of chromatide, when one shoulder is longer, and the second is shorter.
• ACROCENTRIC or ropyoid. They have a centromer located almost at the very end of the chromosome.

Functions chromosomes

The main functions of chromosome, both for animals and plants and in general all living beings - the transfer of hereditary, genetic information from parents to children.

Set of chromosomes

The chromosome value is so large that their number in cells, as well as the features of each chromosome, determine the characteristic feature of a particular biological species. For example, the flies of frosophila in the presence of 8 chromosomes, y - 48, and the chromosomal set of a person is 46 chromosomes.

In nature, there are two main types of chromosomes: single or haploid (contained in germ cells) and double or diploid. The diploid set of chromosomes has a paired structure, that is, the entire totality of chromosomes consists of chromosomal pairs.

Chromosomal set of man

As we have already written above, the cells of the human body contain 46 chromosomes, which are combined into 23 pairs. All together they constitute a chromosomal set of man. The first 22 pairs of human chromosomes (they are called autosomes) are common for both men and women, and only 23 pairs - sex chromosomes - will be varied from different floors, it also defines a person's sexuality. The combination of all pairs of chromosomes is also called a karyotype.

This species has a chromosomal set of man, 22 pairs of double diploid chromosomes contain all of our hereditary information, and the last pair differs, in men, it consists of a pair of conditioner X and Y genital chromosomes, while in women in the presence of two chromosomes H.

All animals are similar to the structure of the chromosomal set, only the number of non-chromosomes each of them has its own.

Genetic diseases associated with chromosomes

Violation in the work of chromosomes, or even their very incorrect amount is the cause of many genetic diseases. For example, Down syndrome appears due to the presence of excess chromosome in a chromosomal human set. And genetic diseases such as daltonism, hemophilia is caused by failures in the work of the existing chromosomes.

Chromosome, video

And in conclusion, an interesting educational video about chromosome.

This article is available in English.

Sometimes the surprises are presented to us. For example, do you know what chromosome is and how do they affect?

We suggest to understand this issue, in order to place all the points over "I" once and forever.

Considering family photos, you probably could see that the members of one kinship are similar to each other: children - on parents, parents - grandparents. This similarity is transmitted from generation to generation with amazing mechanisms.

All living organisms, from unicellular to African elephants, in the core cells are chromosomes - thin long threads that can only be considered in an electronic microscope.

Chromosome (Dr. Greek. Χρῶμα - the color and σῶμα - the body) is nucleoprotional structures in the cell core, in which most of the hereditary information (genes) is concentrated. They are designed to store this information, its implementation and transmission.

How many chromosomes in humans

At the end of the XIX century, scientists found out that the number of chromosomes in different species is not the same.

For example, in pea 14 chromosomes, y - 42, and in humans - 46 (that is, 23 pairs). Hence the temptation arises to conclude that what they are more - the more difficult creature with them. However, in fact, it is completely wrong.

Of 23 pairs of human chromosomes 22 pairs - autosomes and one pair - gonomome (sex chromosomes). File have morphological and structural (gene composition) differences.

The female body a couple has two x-chromosomes (XX steam), and in a male - one x and y-chromosome (XY-steam).

It is from what is the composition of the chromosomes of the twenty-third pair (XX or XY), the floor of the future child depends. This is determined when fertilizing and merging the female and male genital cell.

This fact may seem strange, but by the number of chromosomes, a person is inferior to many animals. For example, at some unfortunate goat 60 chromosomes, and snail is 80.

Chromosomes Consist of protein and DNA molecules (deoxyribonucleic acid), similar to a double helix. Each cage is about 2 meters of DNA, and in total in the cells of our body about 100 billion km DNA.

It is interesting that if there is an extra chromosome or in the absence of at least one of 46, - a person has mutations and serious deviations in development (Dauna disease, etc.).