genetic types. Genetic types of wall rocks

Genetics- the science that studies heredity and variability of organisms.
Heredity- the ability of organisms to transmit their characteristics from generation to generation (features of structure, functions, development).
Variability- the ability of organisms to acquire new traits. Heredity and variability are two opposite but interrelated properties of an organism.

Heredity

Basic concepts
Gene and alleles. The unit of hereditary information is the gene.
Gene(from the point of view of genetics) - a section of the chromosome that determines the development of one or more traits in an organism.
alleles- different states of the same gene, located in a certain locus (region) of homologous chromosomes and determining the development of some kind of trait. Homologous chromosomes are found only in cells containing a diploid set of chromosomes. They are not found in germ cells (gametes) of eukaryotes and prokaryotes.

Sign (hair dryer)- some quality or property by which one organism can be distinguished from another.
domination- the phenomenon of the predominance of the trait of one of the parents in the hybrid.
dominant trait- a trait that appears in the first generation of hybrids.
recessive trait- a trait that outwardly disappears in the first generation of hybrids.

Dominant and recessive traits in humans

signs
dominant	recessive
Dwarfism	normal growth
Polydactyly (multi-fingeredness)	Norm
curly hair	Straight hair
Not red hair	Red hair
early baldness	Norm
Long eyelashes	short eyelashes
big eyes	Small eyes
Brown eyes	Blue or gray eyes
Myopia	Norm
Twilight vision (night blindness)	Norm
Freckles on the face	No freckles
Normal blood clotting	Weak blood clotting (hemophilia)
color vision	Lack of color vision (color blindness)

dominant allele - an allele that determines a dominant trait. It is indicated by a Latin capital letter: A, B, C, ....
recessive allele - an allele that determines a recessive trait. It is indicated by a Latin lowercase letter: a, b, c, ....
The dominant allele ensures the development of the trait both in the homo- and heterozygous state, the recessive allele appears only in the homozygous state.
Homozygous and heterozygous. Organisms (zygotes) can be homozygous or heterozygous.
Homozygous organisms have two identical alleles in their genotype - both dominant or both recessive (AA or aa).
Heterozygous organisms have one of the alleles in the dominant form, and the other in the recessive form (Aa).
Homozygous individuals do not cleave in the next generation, while heterozygous individuals give cleavage.
Different allelic forms of genes arise as a result of mutations. A gene can mutate repeatedly, producing many alleles.
Multiple allelism - the phenomenon of the existence of more than two alternative allelic forms of a gene that have different manifestations in the phenotype. Two or more states of a gene result from mutations. A series of mutations causes the appearance of a series of alleles (A, a1, a2, ..., an, etc.), which are in different dominant-recessive relationships to each other.
Genotype is the totality of all the genes of an organism.
Phenotype - the totality of all the characteristics of an organism. These include morphological (external) signs (eye color, flower color), biochemical (shape of a structural protein or enzyme molecule), histological (cell shape and size), anatomical, etc. On the other hand, signs can be divided into qualitative ( eye color) and quantitative (body weight). The phenotype depends on the genotype and environmental conditions. It develops as a result of the interaction of the genotype and environmental conditions. The latter affect the qualitative features to a lesser extent and the quantitative ones to a greater extent.
Crossing (hybridization). One of the main methods of genetics is crossing, or hybridization.
hybridological method - crossing (hybridization) of organisms that differ from each other in one or more characteristics.
hybrids - descendants from crosses of organisms that differ from each other in one or more characteristics.
Depending on the number of signs by which the parents differ from each other, different types of crossing are distinguished.
monohybrid cross A cross in which the parents differ in only one trait.
Dihybrid cross A cross in which the parents differ in two ways.
Polyhybrid cross - crossbreeding, in which parents differ in several ways.
To record the results of crosses, the following generally accepted notation is used:
P - parents (from lat. parental- parent);
F - offspring (from lat. filial- offspring): F 1 - hybrids of the first generation - direct descendants of parents P; F 2 - second generation hybrids - descendants from crossing F 1 hybrids among themselves, etc.
♂ - male (shield and spear - a sign of Mars);
♀ - female (a mirror with a handle - a sign of Venus);
X - cross icon;
: - splitting of hybrids, separates the digital ratios of different (by phenotype or genotype) classes of descendants.
The hybridological method was developed by the Austrian naturalist G. Mendel (1865). He used self-pollinating garden pea plants. Mendel crossed pure lines (homozygous individuals) that differ from each other in one, two or more traits. He received hybrids of the first, second, etc. generations. Mendel processed the data obtained mathematically. The results obtained were formulated in the form of laws of heredity.

G. Mendel's laws

Mendel's first law. G. Mendel crossed pea plants with yellow seeds and pea plants with green seeds. Both were pure lines, that is, homozygotes.

Mendel's first law - the law of uniformity of hybrids of the first generation (the law of dominance): when crossing pure lines, all hybrids of the first generation show one trait (dominant).
Mendel's second law. After that, G. Mendel crossed hybrids of the first generation among themselves.

Mendel's second law - the law of feature splitting: hybrids of the first generation, when they are crossed, split in a certain numerical ratio: individuals with a recessive manifestation of a trait make up 1/4 of the total number of descendants.

Splitting is a phenomenon in which the crossing of heterozygous individuals leads to the formation of offspring, some of which carry a dominant trait, and some are recessive. In the case of monohybrid crossing, this ratio looks like this: 1AA:2Aa:1aa, that is, 3:1 (in case of complete dominance) or 1:2:1 (in case of incomplete dominance). In the case of dihybrid crossing - 9:3:3:1 or (3:1) 2 . With polyhybrid - (3:1) n.
incomplete dominance. The dominant gene does not always completely suppress the recessive gene. Such a phenomenon is called incomplete dominance . An example of incomplete dominance is the inheritance of the color of the flowers of the night beauty.

Cytological basis of uniformity of the first generation and splitting of characters in the second generation consist in the divergence of homologous chromosomes and the formation of haploid germ cells in meiosis.
Hypothesis (law) of purity of gametes states: 1) during the formation of germ cells, only one allele from an allelic pair enters each gamete, that is, the gametes are genetically pure; 2) in a hybrid organism, genes do not hybridize (do not mix) and are in a pure allelic state.
Statistical nature of splitting phenomena. From the hypothesis of purity of gametes it follows that the law of splitting is the result of a random combination of gametes carrying different genes. With the random nature of the connection of gametes, the overall result turns out to be natural. It follows that with monohybrid crossing, the ratio of 3:1 (in the case of complete dominance) or 1:2:1 (in the case of incomplete dominance) should be considered as a pattern based on statistical phenomena. This also applies to the case of polyhybrid crossing. The exact fulfillment of numerical ratios during splitting is possible only with a large number of hybrid individuals studied. Thus, the laws of genetics are statistical in nature.
offspring analysis. Analyzing cross allows you to determine whether an organism is homozygous or heterozygous for a dominant gene. To do this, an individual is crossed, the genotype of which should be determined, with an individual homozygous for the recessive gene. Often one of the parents is crossed with one of the offspring. Such a crossing is called returnable .
In the case of homozygosity of the dominant individual, splitting will not occur:

In the case of heterozygosity of the dominant individual, splitting will occur:

Mendel's third law. G. Mendel carried out a dihybrid crossing of pea plants with yellow and smooth seeds and pea plants with green and wrinkled seeds (both pure lines), and then crossed their descendants. As a result, he found that each pair of traits during splitting in the offspring behaves in the same way as during monohybrid crossing (it splits 3: 1), that is, regardless of the other pair of traits.

Mendel's third law- the law of independent combination (inheritance) of traits: splitting for each trait occurs independently of other traits.

Cytological basis of independent combination is the random nature of the divergence of homologous chromosomes of each pair to different poles of the cell during meiosis, regardless of other pairs of homologous chromosomes. This law is valid only when the genes responsible for the development of different traits are located on different chromosomes. Exceptions are cases of linked inheritance.

Linked inheritance. Clutch failure

The development of genetics has shown that not all traits are inherited in accordance with Mendel's laws. Thus, the law of independent inheritance of genes is valid only for genes located on different chromosomes.
The patterns of linked inheritance of genes were studied by T. Morgan and his students in the early 1920s. 20th century The object of their research was the Drosophila fruit fly (its life span is short, and several dozen generations can be obtained in a year, its karyotype consists of only four pairs of chromosomes).
Morgan's Law: genes located on the same chromosome are predominantly inherited together.
Linked genes are genes that are on the same chromosome.
clutch group All genes on one chromosome.
In a certain percentage of cases, the clutch may be broken. The reason for the violation of linkage is crossing over (crossing of chromosomes) - the exchange of sections of chromosomes in prophase I of meiotic division. Crossover leads to genetic recombination. The farther apart the genes are, the more often crossing over occurs between them. This phenomenon is based on the construction genetic maps- determination of the sequence of genes in the chromosome and the approximate distance between them.

Sex Genetics

autosomes Chromosomes are the same for both sexes.
Sex chromosomes (heterochromosomes) Chromosomes that distinguish males and females from each other.
A human cell contains 46 chromosomes, or 23 pairs: 22 pairs of autosomes and 1 pair of sex chromosomes. Sex chromosomes are referred to as X- and Y-chromosomes. Women have two X chromosomes, while men have one X and one Y chromosome.
There are 5 types of chromosomal sex determination.

Types of chromosomal sex determination

Type of	Examples
♀XX, ♂XY	Characteristic for mammals (including humans), worms, crustaceans, most insects (including fruit flies), most amphibians, some fish
♀ XY, ♂ XX	Characteristic for birds, reptiles, some amphibians and fish, some insects (lepidoptera)
♀ XX, ♂ X0	Occurs in some insects (Orthoptera); 0 means no chromosomes
♀ Х0, ♂ XX	Found in some insects (Hydroptera)
haplo-diploid type (♀ 2n, ♂ n)	It occurs, for example, in bees and ants: males develop from unfertilized haploid eggs (parthenogenesis), females develop from fertilized diploid ones.

sex-linked inheritance - inheritance of traits whose genes are located on the X and Y chromosomes. The sex chromosomes may contain genes that are not related to the development of sexual characteristics.
When XY is combined, most of the genes located on the X chromosome do not have an allele pair on the Y chromosome. Also, genes located on the Y chromosome do not have alleles on the X chromosome. Such organisms are called hemizygous . In this case, a recessive gene appears, which is present in the genotype in the singular. So the X chromosome may contain a gene that causes hemophilia (reduced blood clotting). Then all male individuals who received this chromosome will suffer from this disease, since the Y chromosome does not contain a dominant allele.

blood genetics

According to the AB0 system, people have 4 blood groups. The blood group is determined by gene I. In humans, the blood group is provided by three genes IA, IB, I0. The first two are co-dominant with respect to each other, and both are dominant with respect to the third. As a result, a person has 6 blood groups according to genetics, and 4 according to physiology.

I group	0	I 0 I 0	homozygous
II group	BUT	I A I A	homozygous
		I A I 0	heterozygote
III group	AT	I B I B	homozygous
		I B I 0	heterozygote
IV group	AB	I A I B	heterozygote

In different peoples, the ratio of blood groups in the population is different.

Distribution of blood groups according to the AB0 system among different peoples,%

In addition, the blood of different people can differ in the Rh factor. Blood can be Rh positive (Rh+) or Rh negative (Rh-). This ratio varies among different peoples.

The distribution of the Rh factor in different peoples,%

Nationality	Rh positive	Rh negative
australian aborigines	100	0
American Indians	90–98	2–10
Arabs	72	28
Basques	64	36
Chinese	98–100	0–2
Mexicans	100	0
Norse	85	15
Russians	86	14
Eskimos	99–100	0–1
Japanese	99–100	0–1

The Rh factor of the blood determines the R gene. R + gives information about the production of a protein (Rh-positive protein), but the R gene does not. The first gene dominates the second. If Rh + blood is transfused to a person with Rh - blood, then specific agglutinins are formed in him, and repeated administration of such blood will cause agglutination. When an Rh woman develops a fetus that has inherited a positive Rh from the father, an Rh conflict may occur. The first pregnancy, as a rule, ends safely, and the second - with a disease of the child or stillbirth.

Gene Interaction

A genotype is not just a mechanical set of genes. This is a historically established system of genes interacting with each other. More precisely, it is not the genes themselves (sections of DNA molecules) that interact, but the products formed on their basis (RNA and proteins).
Both allelic and non-allelic genes can interact.
Interaction of allelic genes: complete dominance, incomplete dominance, co-dominance.
Complete dominance - the phenomenon when a dominant gene completely suppresses the work of a recessive gene, as a result of which a dominant trait develops.
incomplete dominance - a phenomenon when a dominant gene does not completely suppress the work of a recessive gene, as a result of which an intermediate trait develops.
Codominance (independent manifestation) - a phenomenon when both alleles participate in the formation of a trait in a heterozygous organism. In humans, a series of multiple alleles represents the gene that determines the blood type. In this case, the genes that determine blood types A and B are codominant with respect to each other, and both are dominant with respect to the gene that determines blood type 0.
Interaction of non-allelic genes: cooperation, complementarity, epistasis and polymerism.
Cooperation - a phenomenon when, with the mutual action of two dominant non-allelic genes, each of which has its own phenotypic manifestation, a new trait is formed.
complementarity - the phenomenon when a trait develops only with the mutual action of two dominant non-allelic genes, each of which individually does not cause the development of a trait.
epistasis - the phenomenon when one gene (both dominant and recessive) suppresses the action of another (non-allelic) gene (both dominant and recessive). The suppressor gene (suppressor) can be dominant (dominant epistasis) or recessive (recessive epistasis).
Polymerism - the phenomenon when several non-allelic dominant genes are responsible for a similar effect on the development of the same trait. The more such genes present in the genotype, the more pronounced the trait. The phenomenon of polymerism is observed in the inheritance of quantitative traits (skin color, body weight, milk yield of cows).
In contrast to polymers, there is such a phenomenon as pleiotropy - multiple gene action, when one gene is responsible for the development of several traits.

Chromosomal theory of heredity

The main provisions of the chromosome theory of heredity:

• Chromosomes play the leading role in heredity;
• genes are located on the chromosome in a certain linear sequence;
• each gene is located in a certain place (locus) of the chromosome; allelic genes occupy the same loci in homologous chromosomes;
• genes of homologous chromosomes form a linkage group; their number is equal to the haploid set of chromosomes;
• between homologous chromosomes, the exchange of allelic genes (crossing over) is possible;
• the frequency of crossing over between genes is proportional to the distance between them.

Nonchromosomal inheritance

According to the chromosome theory of heredity, the DNA of chromosomes plays a leading role in heredity. However, DNA is also found in mitochondria, chloroplasts, and in the cytoplasm. Non-chromosomal DNA is called plasmids . Cells do not have special mechanisms for the uniform distribution of plasmids during division, so one daughter cell can receive one genetic information, and the second - a completely different one. The inheritance of genes contained in plasmids does not follow the Mendelian laws of inheritance, and their role in the formation of the genotype is still poorly understood.

In the biosphere of planet Earth there are biological species, in which any genetically healthy individual - by the mere fact of his birth in this species - has already taken place as a full-fledged representative of this species. An example of this are mosquitoes, other insects, most fish, living lizards. If not all the information support of their behavior, then the vast majority of the algorithms of their behavior is genetically programmed, is innate. The flexibility of the behavior of individuals is minimal - combinatorial based on genetic (innate) information. The share of information support of behavior, which is the result of the accumulation of experience in interaction with the environment by a particular individual or some set of individuals (for example, a flock) - if there is, then it is negligible.

Already in behavior higher animals not innate information prevails, but acquired in the process of upbringing in childhood and accumulated by individuals as an experience of interaction with the environment of each of them. This information is a kind of superstructure over the foundation of the innate information support of behavior (unconditioned reflexes and instincts). But different buildings can be built on the same foundation.

The most important element of the current biosphere of the planet is chromosomal apparatus of cell nuclei characteristic of the vast majority of its biological species. Although the chromosome apparatus is the most important component in the biology of most species in the Earth's biosphere, it does not represent the entire genetic mechanism (mechanism for the transmission of hereditary information) not only of the species as a whole, but also of the individual considered separately. And what he represents only one of the components of the genetic mechanism of the species as a whole, must always be remembered when it comes to heredity, since in the genetics of every species and the biosphere as a whole, there are phenomena that cannot be explained on the basis of combinatorics of the transfer of genes along with chromosomes from the organisms of parents to the organisms of their children . In the genetic mechanism of a species, which includes processes occurring both at the level of biofield structures and at the level of substance structures, the chromosome apparatus is involved in the implementation of two functions vital for the existence of any biological species.

Firstly, it transmits from parent organisms to descendant organisms in the continuity of generations genetically determined - innate information, mostly related to the structure of the molecules of the substance of their bodies, which determines first of all, the bodily characteristics of the individual and many of its other capabilities. The share of distortions in the transmission of genetic information based on the chromosome apparatus under natural conditions is quite low, due to the fact that cells have mechanisms for restoring chromosome sections damaged by various mutagenic factors (this is one of the means that ensures the stability of species in the biosphere over many generations) .

Secondly, those distortions of genetic information that do not have time to eliminate the intracellular and general species systems for protecting and restoring information in the chromosome apparatus are also partially necessary to ensure the conservation and development of the species in the biosphere. This side of the functioning of the chromosomal apparatus needs to be explained.

Distortions of genetic information in chromosomes - mutations - for the most part arise due to the impact on DNA molecules in chromosomes of external factors: physical fields, chemical compounds that are not characteristic of normal cell physiology, etc. Some mutations are genetic defects, since individuals with them in their genotype are either not viable, or infertile, or have a reduced potential for health and development. Such mutations are called genetic cargo . In each population there is a certain proportion of genetically burdened individuals - this is natural for the biosphere.

In fairly large populations, there is always a genetically stable core that ensures the reproduction of new generations and a genetically burdened, degenerating, degrading periphery in subsequent generations. But there is no impassable abyss between them: the boundary between them in the continuity of generations is statistically determined by the combinatorics of the chromosome apparatus, as a result of which the descendants of representatives of the genetic core can replenish the degenerate periphery, and the descendants of degenerates can enter the genetic core of future generations. A genetic catastrophe in a population is the disappearance of a genetically stable core that ensures the adjustment of the species to slowly (in relation to the change of generations) changing environmental conditions.

Some mutations do not have a direct effect on the occurrence of genetically determined defects in organisms and lead only to the appearance in individuals of a species of peculiar traits that have not previously been found in the population. In addition, some of the mutations in the same conditions(both external and internal, genetically determined) can act as a genetic cargo, and in others as a very useful trait. This is collectively called non-directional variability , and it plays an important role in maintaining the stability of biocenoses and the biosphere as a whole.

Each biological species is in interaction with the rest of the biosphere and all of nature as a whole, is under their pressure, and itself puts pressure on them. The nature of this pressure on the species changes due to the subordination of the biosphere to the geological processes on the Earth and the energy-informational rhythms of the Cosmos. The frequencies of some of these processes are significantly lower than the frequency of generational change in any of the genealogical lines of the species. Due to this ratio of the frequencies of external (in relation to the species) processes, non-directional variability results in the adjustment of the species genotype to slowly (in relation to the change of generations) changing environmental conditions. Such is the mechanism of natural selection, which predetermines, probabilistically and statistically, the death of some individuals and the development of others in a particular situation: if the situation were different, the statistics of death and development of individuals would be different.

But there are processes in nature that belong to frequency ranges higher than the frequency of generational change in genealogical lines. Each individual of the species must be adapted to the change in the nature of the pressure on the species caused by them. Otherwise, the population, faced with this kind of pressure from the external environment, to which the genotype does not have time to adjust during the change of generations, and to which the individuals of the species are not adapted, will suffer damage, up to the disappearance of the species from the biosphere. This can harm many other types of living organisms associated with the first food chains (who eats whom; the scientific term for them is "food chains"). So the whole biocenosis can change, and, in principle, the entire biosphere.

The reaction of a biological species to the external pressure of the environment manifests itself in two ways: firstly, a change in the development potential of individuals of a species, due to the adjustment of the genotype in the process of natural selection; Secondly, the behavioral response of an individual to the impact of the environment, directed directly at the individual. Both types of reaction of a biological species require information support. For different biological species, the nature of this information support differs primarily in the volume of behavioral information:

transmitted genetically from generation to generation;

Assimilated by a particular individual during its maturation and adult life;

their ratio, determined by the volume of information support and the social environment (if any) in which the individual is located.

In higher species the amount of extragenetic information underlying the behavior of their individuals, far exceeds the amount of innate behavioral information.

In an adult, the volume extragenetically conditioned (mainly socially conditioned) individual behavioral information suppresses genetically determined information to such an extent that the majority of the population, at least the urban population, no longer feels and is not aware of its individual accessories even to one of the many species of living organisms, not to mention their belonging to the Earth's biosphere as a whole and the conditionality of the life of each of them and the life of their descendants by objective predestinations of the existence of the biosphere.

In addition to conscious connections, unconscious mental and general biological connections with nature are also violated, since city, being not only an insulator from natural biofields, but also a generator of man-made fields, it is one of the most powerful mutagenic factors, and the human genetic apparatus is 50 times more sensitive to them than the apparatus of the notorious Drosophila fly. Thus man opposes himself to Nature. This opposition is the direct cause global biosphere-ecological and other private global crises.

An increase in the relative and absolute volume of extragenetically conditioned behavioral information was accompanied by an expansion of the adaptive capabilities of individuals of species, a decrease in individual dependence their individuals from changes in environmental conditions.

Behavioral reactions of individuals of species in which genetically determined behavior predominates do not differ in variety. For this reason, the inflexibility of the behavior of individuals of a species, which leads to their death, is compensated by high fecundity, the growth of passive and active protection against the effects of adverse factors, which is simply necessary for the existence of such a species. The period of childhood of individuals in such species is either absent or very short. If a factor arises, under the pressure of which the genotype of the population does not have time to adjust during the change of generations, then the population dies.

The need to master large volumes of non-genetically determined behavioral information is accompanied by advent of childhood , during which the individual accumulates the vital minimum of this information, either individually or under the care of adults.

If a factor arises under the influence of which the genotype of a population of such a species cannot have time to adapt when changing generations in the case of exclusively genetically determined (i.e., uniform in different individuals) behavioral reactions, then the population can be preserved due to the diversity of behavioral reactions of its individuals, determined individually non-genetically . This leads to a decrease in the damage caused to the population by this factor and increases the time during which the genetically stable core of the population can potentially adjust to the impact of this factor at the level of the chromosome apparatus. The same applies to the survival of populations during natural disasters and natural disasters in their habitat.

The development potential of each individual of a biological species, in the behavior of which the amount of extragenetically transmitted information is significant, in terms of all the qualities that characterize the individual, genetically determined, although it may not open up, not be filled with real content, if the environmental conditions do not favor it , which is manifested in the fate of real "Mowgli". In relation to the population, genetic conditioning and the potential for its development are subordinated to probabilistic predeterminations, reflected in the statistical patterns of what happened.

This applies to the human as well.- a biological species that carries the largest absolute and relative volume (compared to other species of living organisms of the Earth's biosphere) of non-genetically determined behavioral information that provides the greatest flexibility of behavior in a rapidly changing environment. But the species "House of Reason" also has features that none of the other species possesses, the genetic program of which includes childhood and upbringing (training) by the older generations of the younger ones. The two most visible features are:

· a person is genetically characterized by the ability to meaningful articulate speech, thanks to which the experience of those ancestors who were not their contemporaries and could not pass on their life experience to them in direct communication becomes consciously accessible to the younger generations. In all other biological species, learning and transferring experience from individual to individual in some form requires their direct communication.

Human beings are genetically capable of creativity.

But if the genetic ability for meaningful articulate speech, during life in society, is realized for the most part always, then the ability for creativity is not always in demand in social life, and therefore it is not always realized. Furthermore, some types of organization of social life (socio-economic formations) are maliciously constructed in such a way as to suppress the realization and development of the creative abilities of people living in them.

Thanks to the ability to be creative, the possible individual and collective reaction of representatives of the Homo sapiens species to an unpleasant environmental influence is qualitatively different from the reaction of representatives of other species to unpleasant environmental influences.

If classified a variety of reactions to the unpleasant effects of the environment, then for most biological species it can be divided into three classes, whose names we will give conditional: “attack”, “run away”, “accept the impact on yourself, remaining yourself”.

To these three conventionally named classes of individual and collective reactions to the impact of Objective Reality in the Homo sapiens species, two more are added, due to the genetically inherent ability for creativity:

· « bring something new into the environment by changing the qualities of the environment » and/or

· « find something new in yourself by changing the quality of yourself ».

As a result of this kind of creative act, the previously unpleasant factor is either not able to have an effect at all, or has a significantly smaller effect, or ceases to be unpleasant, although the person continues to be within its reach.

In addition to a creative reaction to the unpleasant effects of the environment, a person is capable of exerting a creative impact, based on his inherent anticipation of the pleasant, both in the process of creativity itself and as a result of subsequent interaction with the environment, changed by his creative activity.

At the same time, it would be wrong to think that the ability to create is due to the mind as such. Animals are reasonable, although in different ways, and this will be denied only by those who do not know their life either in nature or at home, together with man. The cat can perform an intellectual feat and guess that in order for him to leave the room, you need to jump on the door handle, hang on it, after which the door will open, because when the handle turns, the latch will not lock the door, and that turns on its hinges.

But the mind of an animal acts in all cases within the bounds of the possible, not established by him, but formed around him. The question of creativity is reduced to the question of whether the mind itself is allowed to determine and appoint new frontiers of the possible. The human mind is allowed from Above.

The creativity of people qualitatively changes the nature of the processes taking place in the biosphere of the planet. If you look at the life of a region in which there is no place for human creativity for some reason ( either the consequences of human activity do not reach there at all, as biocenoses lived in Antarctica for a long time; or where a person does not feel the need for further creativity, which takes place in the primitive cultures of the Stone Age, which remained unchanged in the tropics until the beginning of the twentieth century; or where it takes all the time to ensure life, like the peoples of the Far North), then in biocenoses there is a cyclic fluctuation in the number of each of the species and the proportions of the number of different species, due to the energy-information rhythms of the Earth and Space

. If we consider the life of regions over longer time intervals, then in many of them one can see a cyclical change of biocenoses: forests are replaced by savannas, then savannas are replaced by forests again and, accordingly, the world of vegetation is replaced by animals. world, under the influence of which the plant world changes, and the cyclicity repeats over and over again with periods from several tens to several hundreds of years. And the rhythm of processes of this kind remains unchanged in the corresponding phases of even longer geological processes and in the intervals between geological and astrophysical catastrophes (volcanic eruptions, the rise and fall of land, the shift of the poles, asteroids hitting the planet, etc.), sometimes changing the whole appearance the biosphere of the planet, and not just its individual regions.

Human creativity is able to fit into this natural rhythm, but it can also change its character both on the scale of the life of the biocenoses of the region and on the scale of the biosphere as a whole, which can lead them out of a stable mode of life and transfer them to some other stable mode. At the same time, a person is able to give the biosphere such a quality that he himself - such as he is now - will not have a place in the new biosphere (called an "ecological niche" in scientific terminology), and the process of changing the biosphere to a form unacceptable for a current person can proceed in such a way quickly that the genetic mechanism of Homo sapiens will be too slow to adapt to these changes. This is the danger of the biosphere-ecological crisis of our time.

But human creativity is able to change the person himself within the limits of the predetermined from Above genetically incorporated potential of his development (in the range from personal to general). At the same time, the genetically incorporated development potential will be mastered, which is equivalent to the completion of the history of the current global civilization and the transition of humanity transformed in this way to a different quality of personal and social life.

After we have decided on the understanding of creativity and the wide range of possibilities for its impact on the planet's biosphere, we can clarify, detail and the concept of "culture" ( Based on what has been said in this and previous chapters), and as a consequence, to decide on the understanding of the correlation of genetic and cultural factors in the life of human societies and the conditionality of both of them for human dignity .

Culture - all not genetically transmitted ready to use information that is the result of the creativity of previous generations. The potential to carry the culture inherited from the ancestors on the basis of social organization is genetically transmitted, and the potential for creativity, i.e. further development of culture.

At the same time, culture being the product of the people themselves , embodied in matter (the so-called material culture) and in physical fields (mostly the so-called spiritual culture), radiated by people and their technosphere, appears as a factor of environmental pressure on all types of living organisms, including humanity itself.

This pressure of culture on biological species, and above all, on humanity itself and its subgroups, is threefold in nature:

Firstly, the achievements (attributes) of culture, invariably characteristic of it throughout the life of many generations;

Secondly, the achievements of the culture of a one-time impulsive nature, declaring themselves throughout the life of one generation;

Thirdly, the achievements (attributes) of culture of a high-frequency nature (in relation to the frequency of updating generations).

In the first case in a culture-bearing society, only those who agree with it and obey its norms get along . All those who oppose the norms of culture that have developed and are stable in the continuity of generations are rejected by the society that carries it: at the same time, they or join other cultures or they die in the struggle with society - the bearer of culture - including leaving no offspring, as a result of which some genes characteristic of them can be preserved in subsequent generations only thanks to the lateral lines of kinship that arose in the previous generations of their ancestors. Respectively it is possible and controlled from Above to proactively advance along the lateral lines to subsequent generations of genetic material that carries information that is not acceptable for the “dominant” culture of earlier generations.

Over these circumstances and their consequences racial hygiene advocates, as a means of liberating society from real and imaginary disasters (disasters - according to their worldview), "genetically programmed", in their vast majority they do not think.

Whether the culture is good or not, whether it is supported by the whole people, or prescribed to it by the “elite” (its “small people”) or by international forces implanting it by means of mafia or state policy, it does not matter. Just under a culture that has been stable for several generations, as under any environmental factor, the genetic mechanism in the continuity of generations adjusts the genetic parameters of the population. At the same time, culture suppresses or frees from past oppression the genetic potential of personal and social development. In what direction does culture affect the innate development potential, This determines whether it is good or bad.. The specific meaning of the words "Good" and "Evil", "Vice" in each historical epoch must be thought about by the people themselves, correlating the words with the prevailing life circumstances and the direction of their change.

If a certain culture becomes common to genetically heterogeneous subgroups in humanity, then after several generations, the genetic mechanism will ensure that the innate qualities in each of the genetically initially different groups correspond to the culture that unites them. This does not mean that the genetic originality of each of the groups will completely disappear, but something common will appear for them.

So the Russians and Bulgarians, thanks to the ancient unity of a culture common to them in many respects, became in a sense brothers, initially being different from the point of view of anthropology and preserving these differences to this day; but also due to cultural separation over many generations, the once innate brotherhood with the Poles was lost. But this process is not localized exclusively in the mechanism of synthesis of DNA molecules and combinatorics of gene exchange based on the chromosome apparatus: it also has biofield components that are not fixed either by anthropology, which is mostly engaged in the comparison of bone remains, or by molecular genetics.

In the second case changes occur in culture during the life of one generation, which, at the time of their occurrence, are essentially are a proposal to society to qualitatively change its former culture. And if the former society, having refused this proposal, turns out to be unable to stop or overcome its spread among its members, then after the innovation acquires a stable position in culture, albeit an insignificant one, it is able to transfer the role of the genetic core from many individuals with one set genetic parameters to many individuals with some other set of genetic parameters, as a result of which in the future the genetically determined potential for personal and social development will either be suppressed or released by the culture that has changed its quality as a result of this innovation. After that, a certain new culture can gain stability in the continuity of generations and the genetics of the population will adapt to it.

An example of this kind of impulsive influence is the baptism of Rus' and the planting of biblical culture by the power of an “elitized” state, under the yoke of which breeders - managers and owners of the Biblical racial project - breed breeds from birth, uncomplaining slaves who put their minds - even if unconsciously - with insurmountable boundaries, the need to maintain his slave status. In Russia, this process of purposeful slave selection continues to the present for the 1000th anniversary of the baptism of Rus' and reached its greatest strength in the “golden age” of Catherine II, as a result of which, during the time of Nicholas I, during the implementation of recruitment sets, a massive degeneration of serfs was noted, in terms of their indicators inferior to the miraculous heroes of the times of A.V. Suvorov. But by our time, this process of breeding and selecting the race of slaves has lost stability and is being destroyed.

An example of the same kind of impulsive impact is the cultural revolution after 1917, as a result of which the cultural and ideological basis for the clan division in the USSR of any people into a “big people” and its heterogeneous “elites” was destroyed, forming a “small people” in its composition, as a result of which it was the regional civilization of Russia that was the first to go into space, resolving all technical and organizational problems on its own.

This take-off was also stopped by an impulse impact on culture - the active imposition of the “cultural” use of alcoholic (and, above all, low-alcohol) drinks and smoking: a rare film, starting from the late 1930s, did without showing festive feasts with the participation of drinking and smoking goodies. who became role models for youth.

alcohol causes mutations, as a result of which the genes damaged by it are passed on to offspring, destroying the potential for health and personal development of subsequent generations;

In addition to mutations, alcohol can cause failures in the development of genetic programs that are infallible in themselves, both in the body of the drinker and in the process of the formation of the fetus in the body of the drinking mother.

For many people, genetically - in the process of cultural drinking without abuse - the emergence of dependence on alcohol consumption is programmed, which inevitably develops into alcoholism with its characteristic companions: destruction of the neural networks of the brain, degradation of the personality, general progressive deterioration in health, genetic disorders in the offspring and fixation predisposition to alcoholism at the genetic level.

Due to the fact that alcohol is a mutagenic drug, and the genetic predisposition to the emergence of dependence on alcohol is an objective reality, anyone who opposes propaganda and the establishment of absolute sobriety in relation to alcohol as a norm of human life (as well as other intoxicants that have similar more or less pronounced pronounced impact) - either a fool or a scoundrel, dooming many people in several generations to a flawed existence, to a reduced potential for their personal development, which lowers the potential for social development as a whole, and also poses a threat to others when something turns out to be in the power of the drinker. other than his body.

Therefore, everything that has been said about the impulsive impact on culture, first of all, concerns the emergence and spread of cultural attributes that have a direct impact on the genetics of the society that carries culture.

In the third case, when something in culture repeatedly appears and disappears many times during the lifetime of one generation (which is an example of the alternation of fashion today for mini- and maxi-skirts, for the complete closeness of the body and nakedness, including the nakedness of its parts, traditionally revered as " intimate"), then for the functioning of the genetic mechanism of the species and its subgroups, this is high-frequency noise, to which it simply does not have time to respond. But if in a culture some low-frequency or impulsive process is associated with a certain high-frequency process, which has influence in the sense described earlier, then the genetic mechanism of societies will adapt to these low-frequency and impulsive processes.

Now again let's return to the consideration of the work of the chromosomal apparatus, as one of the components of the species genetic mechanism. The chromosome apparatus of multicellular organisms in each biological species includes its uniquely defined number of uniquely constructed chromosomes. In all bisexual species, the chromosomes are paired; paired chromosomes are called homologous. In each pair, one chromosome is obtained from the chromosome apparatus of the paternal organism, and the other from the chromosome apparatus of the maternal organism. For the same trait in the body (or a set of related traits), some gene (fragment of a chromosome that carries information that controls that trait). Accordingly, each trait at the chromosome level is recorded twice in any organism: once in the corresponding gene of one chromosome, the second time in the corresponding gene of the paired chromosome. As a result, the same feature can be defined in different ways. A normally unambiguous definiteness is introduced into the structure of an organism by the fact that all genes and their corresponding traits are objectively divided into:

· dominant(strong) - blocking the action of alternative genes that specify the same trait. Dominant genes that are always manifested in the structure of the body (for example, in humans, brown eyes are dominant), regardless of the combination of genes in a pair of chromosomes.

· recessive(weak) genes and traits that do not appear in the body if an alternative dominant gene is present in the chromosome set (for example, in humans, blue eyes are recessive). Recessive traits appear in the structure of the organism only if both genes that determine them in a pair of chromosomes are the same - recessive.

In addition, if a gene in one chromosome turns out to be damaged, sick, then the corresponding signs in the structure of the organism and its functioning are determined not by him, but by the healthy gene of the paired chromosome .

In humans, sex is determined by chromosomes called "X" and "Y" for their similarity to the letters of the Latin alphabet. A man carries a pair of XY chromosomes, a woman a pair of XX. Due to this feature in the body of a man, unlike the body of a woman, the genes of the X chromosome are not duplicated, at least those that the missing leg of the "Y" chromosome should correspond to. As a result, a congenital disease of blood incoagulability (for example, Tsarevich Alexei Nikolayevich was ill with it), caused by a diseased gene on the X chromosome, is much more common in men than in women. But due to the duplication of all the information of the X chromosome in the female body, women rarely get sick of it themselves, and are its secretive distributors in society. In order for a woman to manifest a genetically determined blood incoagulability, it is necessary that the corresponding genes in both of her XX chromosomes be diseased.

This feature of the chromosomal apparatus, built on the pairing of genes responsible for each of the traits (or their interconnected combination), manifests itself in two ways in the life of society of individuals of the Homo sapiens species that carry culture. On the one hand, in closely related marriages, the statistics of hereditary diseases are higher, due to the fact that in a pair, both corresponding gene diseases obtained from the same close relatives turn out to be sick

. On the other hand, if some trait, defined as socially significant and, as a result, giving the advantage of the community in which the proportion of its carriers is greater, is due to a recessive gene, then if there is no known way to turn the “recessive-dominance” ratio in its favor , then the only way to increase the frequency of manifestation of a recessive trait in the offspring is to create conditions for closely related marriages: up to half-brothers and sisters, and parents with their own children (in breeding and selection of breeds of domestic animals, purposeful crossing of closely related individuals is called "inbreeding").

But for an attempt to gain some advantage over other clans and tribes by cultivating inbreeding, one has to pay with hereditary diseases that also accompany the coincidence in the chromosome pairs of the diseased genes accumulating in the population.

.

But the work of the genetic mechanism of the species is not limited to the work of the chromosome apparatus, gene mutations and their combinatorics. A well-known phenomenon called "telegony" . Its essence is visibly shown by such an example. If a zebra stallion copulates with a horse mare, then conception of a foal is impossible due to the fact that the set of chromosomes in the spermatozoa transferred to the mare is incompatible with the set of chromosomes in her egg. However, as a result of the mating of this mare with stallions, horses, she and her descendants can give birth to foals - striped, as is characteristic of zebras.

Due to the objective possibility of inheritance by telegony, for centuries, females have been excluded from breeding work, at least once having copulated with males of other breeds that are undesirable to the breeder, even if such copulation was not followed by the conception and birth of unpurified offspring: thereby breeders of the breed exclude the statistical predetermination of the appearance in its offspring due to telegony traits inherent in breeds that are undesirable in their breeding work, which can spoil the breed they are working on developing.

From the point of view of vulgar materialism, which recognizes only matter and the electromagnetic field as matter, the phenomenon telegony inexplicable (and since attempts to cross a zebra with a horse are infrequent, it can allegedly be forgotten without prejudice to science, agricultural practices and sexual life in society)

. If under biofield understand a set of general natural fields modulated in the coding system according to the information they carry, which are generated by a living organism, then, faced with the manifestations of telegony in the biosphere, it remains to recognize that:

A certain proportion of hereditary information is transmitted to individuals of subsequent generations on the basis of biofields, which close on each other in the process of copulation of individuals of older generations; the transfer of hereditary information through biofields takes place even regardless of whether conception is possible in principle in such copulation or not.

But telegony is not the only phenomenon associated with the work of the genetic mechanism of a biological species as a whole, due to the transfer of information based on biofields. Experiments have been reported in which a control population of laboratory white mice was exposed to a mutagenic factor (alcohol) for several generations. As a result, the proportion of genetically defective individuals sharply increased in it. Those individuals that did not lose the ability to reproduce under the influence of a mutagenic factor also gave genetically defective offspring until the entire population was genetically defective to one degree or another. And it would seem, if we proceed from the statistical-mechanistic traditional ideas about combinatorics in the work of the chromosomal apparatus, this situation should have been preserved in the continuity of generations even after the removal of the influence of the mutagenic factor. But after the influence of the mutagenic factor was removed, after some time it turned out that mice with the chromosomal apparatus undeniably crippled in the past began to produce genetically perfect lines of offspring.

That is the general species genetic mechanism has the ability to correct the accumulated errors in the operation of the chromosome apparatus, affecting the synthesis of gene molecules through biofield structures characteristic of the biological species as a whole.

All information transmitted genetically from parents to children is a multicomponent information system. Its components of different functional purpose must be coordinated with each other. If there are any discrepancies in it, then this is similar to the fact that you are reading a textbook on chemistry and in one of its sections you meet a notification that some aspects of the issue under consideration and other issues related to it are set out in another paragraph of the textbook on page number such and such. You open that page and find that the typography made a mistake and pasted a certain number of pages from the geography textbook into the chemistry textbook, and they also have links to other pages of the geography textbook. As a result, using such a textbook, it is impossible to learn either chemistry or geography.

If this happens with innate information inherited by any individual of a biological species in its natural habitat, then this individual, in comparison with other individuals of the species, has a reduced chance of surviving in the course of natural selection that takes place in the life of the biocenosis. As a result, populations in biocenoses have in their composition a relatively small proportion of individuals with an internally conflicting innate information system due to genetics.

Among the attributes of culture that harm the development of the fetus, even if its genotype is not burdened by mutations and mutual inconsistency of its various information modules, one should name all the same alcohol and smoking. Drinking and smoking mothers and grown-up daughters of mothers who once smoked are much more likely to give birth to premature babies, their offspring are much more likely to have such ailments as cerebral palsy and multiple sclerosis, which are very difficult to treat with current traditional medicine, not to mention the more common and less severe diseases.

However everyone who knows about this kind of effect of alcohol and tobacco is rubbish hopes that her child will avoid such a misfortune even if she continues to use "moderately" low-alcohol drinks or smoke in the period of life before conception and during pregnancy: drinking "in moderation"; the same applies to fathers. The cumulative statistics, as the media periodically report, is such that now only one out of ten babies in Russia is born without any pathology.

At the same time, tobacco advertising has deadly silence: advertising is accompanied by an inscription that "The Ministry of Health warns: smoking is dangerous for your health", but is silent about the fact that smoking is dangerous to the health of your descendants, and it - unlike yours - is not your property. WHEN YOU SMOK AND DRINK, YOU DESTROY WHAT YOU DON'T OWN.

But there are also attributes of culture that seem innocent, in contrast to poorly tested medical drugs, alcohol, tobacco and other drugs, although they can also have a striking mass effect on the bodies of mothers and fetuses. This is primarily cosmetics: the consequences of the daily use of cosmetic drugs that are absorbed through the skin into the body of a woman in the current technosphere are in many cases unpredictable. A mistake by a cosmetics firm or deliberate sabotage by a maniac chemist on its staff can have consequences even more dire than thalidomide has shown in the past. This should also include many food preservatives and fillers: their abundance and diversity, in principle, can lead to the fact that even safe individually, they in the human body in some combinations will have a mutagenic or inhibitory effect on the genetic mechanism, which will have adverse consequences for offspring.

Therefore, in order to look into the eyes of your children and grandchildren without pain and shame, it is better to avoid what can have a mutagenic effect or disrupt the development of an impeccable genetic program in itself: and this applies to both men and women. Problems caused by disturbances in the work of the genetic mechanism are much easier to prevent than to overcome. If not instantly, then in most cases they can be prevented during the reproductive period of life, and if they arise, then descendants will have to overcome them in the continuity of several generations, and they are unlikely to find words of gratitude to their ancestors who created these problems for them.

In real history, if not all individuals, then societies as a whole had some idea of ​​the conditionality of many features of life by heredity and about the reverse influence of lifestyle, culture - on heredity. Such phrases as “voice of blood”, “half-breed”, “not from relatives, but to relatives”, “neither to mother, nor to father, but to a passing young man”, “bad heredity”, “spoil the girl”, “geek” etc. appeared long before Georg Johann Mendel in 1866, based on observation of flowers in the monastery garden and statistical analysis of variability, formulated the laws of inheritance of traits

, and subsequent naturalists explained the mechanism of their action on the basis of the work of the chromosome apparatus.

Genetics- the science of the laws of heredity and variability. The date of the "birth" of genetics can be considered 1900, when G. De Vries in Holland, K. Correns in Germany and E. Cermak in Austria independently "rediscovered" the laws of inheritance of traits established by G. Mendel back in 1865.

Heredity- the property of organisms to transmit their characteristics from one generation to another.

Variability- the property of organisms to acquire new characteristics compared to their parents. In a broad sense, variability is understood as differences between individuals of the same species.

sign- any feature of the structure, any property of the body. The development of a trait depends both on the presence of other genes and on environmental conditions; the formation of traits occurs in the course of individual development of individuals. Therefore, each individual individual has a set of features that are characteristic only for her.

Phenotype- the totality of all external and internal signs of the body.

Gene- a functionally indivisible unit of genetic material, a section of a DNA molecule encoding the primary structure of a polypeptide, a molecule of transport or ribosomal RNA. In a broad sense, a gene is a section of DNA that determines the possibility of developing a separate elementary trait.

Genotype is the totality of an organism's genes.

Locus the location of the gene on the chromosome.

allelic genes- genes located in identical loci of homologous chromosomes.

Homozygote An organism that has allelic genes of the same molecular form.

heterozygote- an organism that has allelic genes of different molecular forms; in this case, one of the genes is dominant, the other is recessive.

recessive gene- an allele that determines the development of a trait only in the homozygous state; such a trait would be called recessive.

dominant gene- an allele that determines the development of a trait not only in the homozygous, but also in the heterozygous state; such a trait will be called dominant.

Genetic methods

The main one is hybridological method- a system of crosses that allows you to trace the patterns of inheritance of traits in a number of generations. First developed and used by G. Mendel. Distinctive features of the method: 1) targeted selection of parents who differ in one, two, three, etc. pairs of contrasting (alternative) stable traits; 2) strict quantitative accounting of the inheritance of traits in hybrids; 3) individual assessment of offspring from each parent in a number of generations.

Crossing, in which the inheritance of one pair of alternative traits is analyzed, is called monohybrid, two pairs - dihybrid, several pairs - polyhybrid. Alternative signs are understood as different values ​​of any sign, for example, a sign is the color of peas, alternative signs are yellow, green peas.

In addition to the hybridological method, genetics uses: genealogical- compilation and analysis of pedigrees; cytogenetic- study of chromosomes; twin- study of twins; population-statistical the method is the study of the genetic structure of populations.

Genetic symbolism

Proposed by G. Mendel, used to record the results of crosses: P - parents; F - offspring, the number below or immediately after the letter indicates the serial number of the generation (F 1 - hybrids of the first generation - direct descendants of the parents, F 2 - hybrids of the second generation - arise as a result of crossing F 1 hybrids with each other); × - crossing icon; G - male; E - female; A - dominant gene, a - recessive gene; AA is homozygous dominant, aa is homozygous recessive, Aa is heterozygous.

The law of uniformity of hybrids of the first generation, or Mendel's first law

The success of Mendel's work was facilitated by the successful choice of an object for crossing - various varieties of peas. Features of peas: 1) relatively easy to grow and have a short period of development; 2) has numerous offspring; 3) has a large number of well-marked alternative characters (corolla color - white or red; cotyledons color - green or yellow; seed shape - wrinkled or smooth; pod color - yellow or green; pod shape - rounded or constricted; arrangement of flowers or fruits - along the entire length of the stem or at its top; stem height - long or short); 4) is a self-pollinator, as a result of which it has a large number of pure lines that stably retain their traits from generation to generation.

Mendel conducted experiments on crossing different varieties of peas for eight years, starting in 1854. On February 8, 1865, G. Mendel spoke at a meeting of the Brunn Society of Naturalists with a report “Experiments on plant hybrids”, where the results of his work were summarized.

Mendel's experiments were carefully thought out. If his predecessors tried to study the patterns of inheritance of many traits at once, then Mendel began his research by studying the inheritance of just one pair of alternative traits.

Mendel took varieties of peas with yellow and green seeds and artificially cross-pollinated them: he removed the stamens from one variety and pollinated them with pollen from another variety. Hybrids of the first generation had yellow seeds. A similar picture was observed in crosses in which the inheritance of other traits was studied: when crossing plants with smooth and wrinkled seed forms, all the seeds of the resulting hybrids were smooth, from crossing red-flowered plants with white-flowered plants, all the seeds obtained were red-flowered. Mendel came to the conclusion that in hybrids of the first generation, only one of each pair of alternative traits appears, and the second, as it were, disappears. Mendel called the trait that appears in hybrids of the first generation dominant, and the trait that is suppressed is recessive.

At monohybrid crossing of homozygous individuals having different values ​​of alternative traits, hybrids are uniform in genotype and phenotype.

Genetic scheme of Mendel's law of uniformity

(A - yellow color of peas, and - green color of peas)

Splitting law, or Mendel's second law

G. Mendel made it possible for hybrids of the first generation to self-pollinate. The hybrids of the second generation thus obtained showed not only a dominant, but also a recessive trait. The results of the experiments are shown in the table.

signs	Dominant		recessive		Total
	Number	%	Number	%
seed shape	5474	74,74	1850	25,26	7324
Coloring of cotyledons	6022	75,06	2001	24,94	8023
Coloration of the seed coat	705	75,90	224	24,10	929
bean shape	882	74,68	299	25,32	1181
bean coloring	428	73,79	152	26,21	580
flower arrangement	651	75,87	207	24,13	858
stem height	787	73,96	277	26,04	1064
Total:	14949	74,90	5010	25,10	19959

Analysis of the data in the table made it possible to draw the following conclusions:

1. uniformity of hybrids in the second generation is not observed: some of the hybrids carry one (dominant), some - the other (recessive) trait from an alternative pair;
2. the number of hybrids carrying a dominant trait is approximately three times more than hybrids carrying a recessive trait;
3. the recessive trait in hybrids of the first generation does not disappear, but is only suppressed and manifests itself in the second hybrid generation.

The phenomenon in which some of the hybrids of the second generation are dominant and some are recessive is called splitting. Moreover, the splitting observed in hybrids is not random, but obeys certain quantitative patterns. Based on this, Mendel made another conclusion: when hybrids of the first generation are crossed in the offspring, the characters are split in a certain numerical ratio.

At monohybrid crossing of heterozygous individuals in hybrids, there is a splitting according to the phenotype in a ratio of 3:1, according to the genotype 1:2:1.

Genetic scheme of Mendel's law of splitting

(A - yellow color of peas, and - green color of peas):

The law of purity of gametes

From 1854, for eight years, Mendel conducted experiments on crossing pea plants. He found that as a result of crossing different varieties of peas with each other, hybrids of the first generation have the same phenotype, and hybrids of the second generation have splitting of characters in certain ratios. To explain this phenomenon, Mendel made a series of assumptions, which are called the "gamete purity hypothesis", or "the law of gamete purity". Mendel suggested that:

1. some discrete hereditary factors are responsible for the formation of traits;
2. organisms contain two factors that determine the development of a trait;
3. during the formation of gametes, only one of a pair of factors enters each of them;
4. when the male and female gametes merge, these hereditary factors do not mix (remain pure).

In 1909, W. Johansen will call these hereditary factors genes, and in 1912, T. Morgan will show that they are located in chromosomes.

To prove his assumptions, G. Mendel used crossing, which is now called analyzing ( analyzing cross- crossing an organism with an unknown genotype with an organism homozygous for the recessive). Perhaps Mendel reasoned as follows: “If my assumptions are correct, then as a result of crossing F 1 with a variety that has a recessive trait (green peas), among the hybrids there will be half green peas and half yellow peas.” As can be seen from the genetic diagram below, he really received a 1:1 split and was convinced of the correctness of his assumptions and conclusions, but he was not understood by his contemporaries. His report "Experiments on plant hybrids", made at a meeting of the Brunn Society of Naturalists, was met with complete silence.

Cytological foundations of the first and second laws of Mendel

At the time of Mendel, the structure and development of germ cells was not studied, so his hypothesis of the purity of gametes is an example of a brilliant foresight, which later found scientific confirmation.

The phenomena of dominance and splitting of characters observed by Mendel are currently explained by the pairing of chromosomes, the divergence of chromosomes during meiosis and their unification during fertilization. Let's designate the gene that determines the yellow color as A, and the green one as a. Since Mendel worked with pure lines, both crossed organisms are homozygous, that is, they carry two identical alleles of the seed color gene (respectively, AA and aa). During meiosis, the number of chromosomes is halved, and only one chromosome from a pair gets into each gamete. Since homologous chromosomes carry the same alleles, all gametes of one organism will contain a chromosome with the A gene, and the other with the a gene.

At fertilization, the male and female gametes fuse and their chromosomes unite in one zygote. The hybrid resulting from crossing becomes heterozygous, since its cells will have the Aa genotype; one variant of the genotype will give one variant of the phenotype - yellow peas.

In a hybrid organism that has the Aa genotype during meiosis, the chromosomes separate into different cells and two types of gametes are formed - half of the gametes will carry the A gene, the other half will carry the a gene. Fertilization is a random and equally probable process, that is, any sperm can fertilize any egg. Since two types of spermatozoa and two types of eggs were formed, four variants of zygotes are possible. Half of them are heterozygotes (carry genes A and a), 1/4 are homozygous for a dominant trait (carry two genes A), and 1/4 are homozygous for a recessive trait (carry two genes a). Homozygotes for the dominant and heterozygotes will give yellow peas (3/4), homozygotes for the recessive - green (1/4).

The law of independent combination (inheritance) of traits, or Mendel's third law

Organisms differ from each other in many ways. Therefore, having established the patterns of inheritance of one pair of traits, G. Mendel moved on to studying the inheritance of two (or more) pairs of alternative traits. For dihybrid crossing, Mendel took homozygous pea plants that differ in seed color (yellow and green) and seed shape (smooth and wrinkled). Yellow color (A) and smooth shape (B) seeds are dominant traits, green color (a) and wrinkled shape (b) are recessive traits.

By crossing a plant with yellow and smooth seeds with a plant with green and wrinkled seeds, Mendel obtained a uniform F 1 hybrid generation with yellow and smooth seeds. From self-pollination of 15 hybrids of the first generation, 556 seeds were obtained, of which 315 yellow smooth, 101 yellow wrinkled, 108 green smooth and 32 green wrinkled (splitting 9:3:3:1).

Analyzing the resulting offspring, Mendel drew attention to the fact that: 1) along with combinations of traits of the original varieties (yellow smooth and green wrinkled seeds), new combinations of traits appear during dihybrid crossing (yellow wrinkled and green smooth seeds); 2) splitting for each individual trait corresponds to splitting during monohybrid crossing. Of the 556 seeds, 423 were smooth and 133 wrinkled (3:1 ratio), 416 seeds were yellow and 140 green (3:1 ratio). Mendel came to the conclusion that splitting in one pair of traits is not associated with splitting in another pair. Hybrid seeds are characterized not only by combinations of traits of parental plants (yellow smooth seeds and green wrinkled seeds), but also by the emergence of new combinations of traits (yellow wrinkled seeds and green smooth seeds).

When dihybrid crossing of diheterozygotes in hybrids, there is a splitting according to the phenotype in a ratio of 9: 3: 3: 1, according to the genotype in a ratio of 4: 2: 2: 2: 2: 1: 1: 1: 1, the characters are inherited independently of each other and combined in all possible combinations.

R	♀AABB yellow, smooth	×	♂aabb green, wrinkled
Types of gametes	AB		ab
F1	AaBb yellow, smooth, 100%
P	♀AaBb yellow, smooth	×	♂AaBb yellow, smooth
Types of gametes	AB Ab aB ab		AB Ab aB ab

Genetic scheme of the law of independent combination of traits:

Gametes:	♂	AB	Ab	aB	ab
♀
AB		AABB yellow smooth	AABb yellow smooth	AaBB yellow smooth	AaBb yellow smooth
Ab		AABb yellow smooth	AAbb yellow wrinkled	AaBb yellow smooth	Aabb yellow wrinkled
aB		AaBB yellow smooth	AaBb yellow smooth	aaBB green smooth	aaBb green smooth
ab		AaBb yellow smooth	Aabb yellow wrinkled	aaBb green smooth	aabb green wrinkled

Analysis of the results of crossing by phenotype: yellow, smooth - 9/16, yellow, wrinkled - 3/16, green, smooth - 3/16, green, wrinkled - 1/16. Segregation by phenotype 9:3:3:1.

Analysis of the results of crossing by genotype: AaBb - 4/16, AABb - 2/16, AaBB - 2/16, Aabb - 2/16, aaBb - 2/16, AABB - 1/16, Aabb - 1/16, aaBB - 1/16, aabb - 1/16. Cleavage by genotype 4:2:2:2:2:1:1:1:1.

If during monohybrid crossing, parent organisms differ in one pair of traits (yellow and green seeds) and give two phenotypes (2 1) in the ratio (3 + 1) 1 in the second generation, then in dihybrid crossing they differ in two pairs of traits and give in the second generation four phenotypes (2 2) in the ratio (3 + 1) 2 . It is easy to calculate how many phenotypes and in what ratio will be formed in the second generation during trihybrid crossing: eight phenotypes (2 3) in the ratio (3 + 1) 3.

If the splitting by genotype in F 2 with a monohybrid generation was 1: 2: 1, that is, there were three different genotypes (3 1), then with a dihybrid, 9 different genotypes are formed - 3 2, with trihybrid crossing 3 3 - 27 different genotypes are formed.

Mendel's third law is valid only for those cases when the genes of the analyzed traits are in different pairs of homologous chromosomes.

Cytological foundations of Mendel's third law

Let A be the gene responsible for the development of yellow seed color, a green seed, B smooth seed, b wrinkled. First-generation hybrids with the AaBb genotype are crossed. During the formation of gametes from each pair of allelic genes, only one gets into the gamete, while as a result of random divergence of chromosomes in the first division of meiosis, gene A can get into one gamete with gene B or with gene b, and gene a - with gene B or with gene b. Thus, each organism forms four varieties of gametes in the same amount (25% each): AB, Ab, aB, ab. During fertilization, each of the four types of sperm can fertilize any of the four types of eggs. As a result of fertilization, nine genotypic classes are possible, which will give four phenotypic classes.

Go to lectures №16"Ontogeny of multicellular animals that reproduce sexually"

Go to lectures №18"Linked Inheritance"

Every person has the desire to continue his race and produce healthy offspring. A certain similarity between parents and children is due to heredity. In addition to the obvious external signs of belonging to the same family, the program of individual development under different conditions is also genetically transmitted.

Heredity - what is it?

The term under consideration is defined as the ability of a living organism to preserve and ensure the continuity of its distinctive features and the nature of development in subsequent generations. It is easy to understand what a person's heredity is by the example of any family. The facial features, physique, appearance in general and the character of children are always as if borrowed from one of the parents, grandparents.

human genetics

What is heredity, features and patterns of this ability is studied by special science. Human genetics is one of its branches. Conventionally, it is classified into 2 types. The main types of genetics:

1. Anthropological- studies the variability and heredity of normal signs of the body. This branch of science is associated with evolutionary theory.
2. Medical– explores the features of the manifestation and development of pathological signs, the dependence of the onset of diseases on environmental conditions and genetic predisposition.

Types of heredity and their characteristics

Information about the specific characteristics of an organism is contained in the genes. Biological heredity is differentiated by their type. Genes are present in cell organelles located in the cytoplasmic space - plasmids, mitochondria, kinetosomes and other structures, and in the chromosomes of the nucleus. Based on this, the following types of heredity are distinguished:

• extranuclear or cytoplasmic;
• nuclear or chromosomal.

Cytoplasmic inheritance

A characteristic feature of the described type of reproduction of specific features is their transmission through the maternal line. Chromosomal inheritance is due mainly to information from the genes of spermatozoa, and extranuclear inheritance is due to eggs. It contains more cytoplasm and organelles responsible for the transmission of individual characteristics. This form of predisposition provokes the development of chronic congenital diseases - diabetes mellitus, tunnel vision syndrome and others.

This type of transfer of genetic information is decisive. Often only he is meant when explaining what human heredity is. The chromosomes of the cell contain the maximum amount of data on the properties of the organism and its specific features. They also contain a development program in certain external environmental conditions. Nuclear inheritance is the transfer of genes embedded in the DNA molecules that make up the chromosomes. It ensures the constant continuity of information from generation to generation.

Signs of human heredity

If one of the partners has dark brown eyes, there is a high probability of a similar shade of the iris in the child, regardless of its color in the second parent. This is due to the fact that there are 2 types of signs of heredity - dominant and recessive. In the first case, individual characteristics are predominant. They suppress recessive genes. The second type of signs of heredity can appear only in the homozygous state. This option occurs if a pair of chromosomes with identical genes is completed in the cell nucleus.

Sometimes a child has several recessive traits at once, even if both parents have them dominant. For example, a dark-skinned baby with blond curls is born to a dark-skinned father and mother with dark hair. Such cases clearly demonstrate what heredity is - not just the continuity of genetic information (from parents to children), but the preservation of all signs of a certain kind within the family, including previous generations. Eye color, hair color and other features can be transmitted even from great-grandparents.

Influence of heredity

Genetics still continues to study the dependence of the characteristics of an organism on its innate properties. The role of heredity in the development and state of human health is not always decisive. Scientists distinguish 2 types of genetic traits:

1. Rigidly determined- are formed before birth, include features of appearance, blood type, and other qualities.
2. Relatively deterministic- highly influenced by the external environment, prone to variability.

When it comes to physical indicators, genetics and health have a pronounced relationship. The presence of mutations in chromosomes and serious chronic diseases in the next of kin determine the general condition of the human body. External signs are completely dependent on heredity. Regarding intellectual development and character traits, the influence of genes is considered relative. Such qualities are more strongly affected by the external environment than by innate predisposition. In this case, it plays a minor role.

Heredity and health

Every expectant mother knows about the influence of genetic characteristics on the physical development of the child. Immediately after the fertilization of the egg, a new organism begins to form, and heredity plays a decisive role in the appearance of specific signs in it. The gene pool is responsible not only for the presence of serious congenital diseases, but also for less dangerous problems - predisposition to caries, hair loss, susceptibility to viral pathologies and others. For this reason, on examination by any doctor, the specialist first collects a detailed family history.

Is it possible to influence heredity?

To answer this question, you can compare the physical performance of several previous and recent generations. Today's youth are much taller, have a stronger physique, good teeth and a high life expectancy. Even such a simplified analysis shows that it is possible to influence heredity. It is even easier to change genetic features in terms of intellectual development, character traits and temperament. This is achieved through the improvement of environmental conditions, correct education and the right atmosphere in the family.

Progressive scientists have long been conducting experiments to assess the impact of medical interventions on the gene pool. Impressive results have been achieved in this area, confirming that it is possible to exclude the occurrence of gene mutations at the stage, prevent the development of serious diseases and mental disorders in the fetus. So far, research has been conducted exclusively on animals. There are several moral and ethical obstacles to starting experiments with the participation of people:

1. By understanding what heredity is, military organizations can use the developed technology to reproduce professional soldiers with improved physical abilities and high health indicators.
2. Not every family can afford to perform the procedure for the most complete egg with the highest quality sperm. As a result, beautiful, talented and healthy children will be born only to wealthy people.
3. Intervention in the processes of natural selection is almost equivalent to eugenics. Most experts in the field of genetics consider it a crime against humanity.

Which contain instructions for the production of protein. According to scientists, the human genome includes about 20,000 genes, but with the development of genetics, their number is constantly decreasing. Genes exist in more than one form. These alternative forms are called alleles, and there are usually two alleles for one trait. Alleles define various traits that can be passed from parent to offspring. The process by which genes are transmitted - was discovered by Gregor Mendel and formulated in the so-called Mendel's law of splitting.

Genes contain genetic codes or sequences of nucleotide bases in nucleic acids to make specific proteins. The information contained in DNA is not directly converted into proteins, but must first be transcribed in a process called DNA transcription. This process takes place in our . The actual production of protein takes place in our cells through a process called translation.