What is meant by genotype and phenotype? The concept of “genotype” and “phenotype”

Genotype - the totality of all the genes of an organism that it receives from its parents.

Phenotype- a set of external and internal signs organisms formed in the process of interaction of genotype and factors environment.

Karyotype- a set of diploid chromosomes of somatic cells of a certain biological species, which is characterized by a constant number, shape, and size.

RELATIONSHIP OF GENOTYPE AND PHENOTYPE.
The totality of all the genes of an organism is called the genotype. A genotype is a collection of genes that interact with each other and influence each other. Each gene is influenced by other genes of the genotype and itself influences them, so the same gene can manifest itself differently in different genotypes.

The set of all properties and characteristics of an organism is called a phenotype. The phenotype develops on the basis of a specific genotype as a result of interaction with environmental conditions. Organisms that have the same genotype may differ from each other depending on the conditions of development and existence. A separate sign is called a hairdryer. Phenotypic characteristics include not only external signs(eye color, hair, nose shape, flower color, etc.), but also anatomical (stomach volume, liver structure, etc.), biochemical (glucose and urea concentration in blood serum, etc.) and others.

If we know the nature of the genetic control of a trait, then we can predict with a certain probability the phenotype based on the genotype (if it is known). If we do not know how a trait is controlled, then we will be completely in the dark, and will not be able to say anything about the traits of future generations. If we know the relationship between genotype and phenotype, then we can make certain predictions about the development of a trait (for example, a disease) and, in some cases, take actions that are beneficial to the individual. To do this, we need to establish the genotype. Now this task is technically solvable (since the human genome has been sequenced), although it is prohibitively expensive.

In reality, we are only given the opportunity to observe the manifestation of a trait in generations and, on the basis of this, create a model of genetic control of the formation of a trait, which can only be true under given specific conditions. But, nevertheless, if we have created such a model, then in this case we can have the means to regulate some characteristic, in particular, influence the occurrence or course of any disease. Thus, genetic control and its study are of great practical, in particular medical, importance. And at the heart of everything are Mendelian patterns, which can manifest themselves differently depending on the specific characteristics of the genotype and environment.

We will now consider what genotype and environmental conditions may exist under which these patterns will not look the same as Mendel observed them, and why this happens. Mendel observed that when the inclinations of two traits are combined in one organism, only one trait can be expressed. The second inclination does not appear. This type of dominance is called complete.

The rediscovery of Mendel's laws led to the identification of other types of dominance. For example, incomplete dominance, when the phenotype of a heterozygote is intermediate between two homozygotes. There is another type of dominance that is very popular in Lately in court, - codominance - in a heterozygote the phenotypes of each of the heterozygotes are manifested. This phenomenon occurs, in particular, in humans. If you have a father's chromosome and a mother's chromosome (and this is undoubtedly the case), and they differ in a million positions, which can be detected by different methods, then these are all cases of codominance.

The primary phenotype of an organism is the nucleotide sequence of its DNA molecules. All phenotypes are based on this phenotype next levels. That is, when examining your DNA, all of your father’s and mother’s characteristics appear; each DNA molecule exhibits its own characteristic regardless of the presence of another DNA molecule with a different characteristic: when sequencing or when DNA is digested by any enzymes, both states of DNA are visible. Codominant characteristics (markers of the DNA molecule itself) characterize the difference between chromosomes and are used to identify a person or establish paternity (the number of such cases resolved in court is several hundred per year).

When we talk about genotype and phenotype, these are extremes of a single process of implementing hereditary information in individual development. For example, the smooth or wrinkled shape of a pea is its phenotype. And the genotype is that specific sequence of nucleotides that, under given conditions, determines that a pea will be smooth or wrinkled. In 1999, a study was carried out with Mendelian pea lines next job. The regions of the chromosome responsible for the shape of the pea were cloned, sequenced, and their features were established - differences in nucleotide sequences - which determined the development of a smooth or wrinkled pea shape.

Please note that the pea shape is the final feature, and the formation of a feature at this level is preceded by the manifestation of the feature at many previous levels. Firstly, it is the presence (allele 1) or absence (allele 2) of an oligosaccharide, which leads to one form or another of the pea. An even deeper level of manifestation of the phenotype is that there is a corresponding protein (allele 1), which is necessary for the synthesis of the oligosaccharide, or it is the same protein, but of an alternative structure (allele 2), in which the oligosaccharide is not formed. An even deeper sign is the RNA with which this protein is synthesized. These RNAs are different in nucleotide sequence (alleles 1 and 2), which makes the corresponding proteins different. And these RNAs are different because they are transcribed from different DNA molecules, father's and mother's, whose nucleotide sequences at a given position are different (alleles 1 and 2). All this is a manifestation of the same phenotype, consistently implemented at each level.

We have the right to talk about phenotype at each of these many levels - from specific features of the DNA nucleotide sequence to the shape of a pea. Moreover, as we move higher from DNA, the greater the influence of environmental conditions. For example, the possibility of functioning of different alleles at the DNA level (transcription of father's and mother's copies of the gene) will depend little on temperature, but the possibility of functioning of the same alleles at the protein level may critically depend on temperature. At some temperatures, a protein (for example, allele 1) will work, but another (allele 2) will not work. As soon as we move to more high level in the implementation of the phenotype, appears more possibilities for the influence of the environment on the manifestation of a trait.

Conversely, the closer we move to the genotype, the more predictable the relationship between genotype and phenotype.

The genotype is the totality of all the genes of an organism, which are its hereditary basis. Phenotype is a set of all signs and properties of an organism that are revealed during the process of individual development under given conditions and are the result of the interaction of the genotype with a complex of factors of the internal and external environment. Phenotype in general is what can be seen (a cat's color), heard, felt (smelled), and the behavior of the animal. In a homozygous animal, the genotype coincides with the phenotype, but in a heterozygous animal, it does not. Each biological species has a phenotype unique to it. It is formed in accordance with the hereditary information contained in the genes. However, depending on changes in the external environment, the state of traits varies from organism to organism, resulting in individual differences - variability. 45. Cytogenetic monitoring in animal husbandry.

The organization of cytogenetic control should be built taking into account a number of basic principles. 1. it is necessary to organize the rapid exchange of information between institutions involved in cytogenetic control; for this purpose, it is necessary to create a unified data bank that would include information about carriers of chromosomal pathology. 2. inclusion of information about the cytogenetic characteristics of the animal in breeding documents. 3. The purchase of seed and breeding material from abroad should be carried out only with a cytogenetic certificate.

Cytogenetic examination in the regions is carried out using information on the prevalence of chromosomal abnormalities in breeds and lines:

1) breeds and lines in which cases of chromosomal pathology transmitted by inheritance have been registered, as well as descendants of carriers of chromosomal abnormalities in the absence of a cytogenetic passport;

2) breeds and lines not previously studied cytogenetically;

3) all cases of massive reproductive disorders or genetic pathology of unknown nature.

First of all, producers and males intended for herd repair, as well as breeding young animals of the first two categories, are subject to examination. Chromosomal aberrations can be divided into two large classes: 1. constitutional - inherent in all cells, inherited from parents or arising during the maturation of gametes and 2. somatic - arising in individual cells during ontogenesis. Taking into account the genetic nature and phenotypic manifestation of chromosomal abnormalities, animals carrying them can be divided into four groups: 1) carriers of heritable abnormalities with a predisposition to a decrease in reproductive qualities by an average of 10%. Theoretically, 50% of descendants inherit the pathology. 2) carriers of hereditary anomalies, leading to a clearly expressed decrease in reproduction (30-50%) and congenital pathology. About 50% of descendants inherit the pathology.

3) Animals with anomalies that arise de novo, leading to congenital pathology (monosomy, trisomy and polysomy in the system of autosomes and sex chromosomes, mosaicism and chimerism). In the vast majority of cases, such animals are infertile. 4) Animals with increased karyotype instability. Reproductive function is reduced, a hereditary predisposition is possible.

46. ​​pleiotropy (multiple action of genes) Pleiotropic action of genes is the dependence of several traits on one gene, that is, the multiple action of one gene. The pleiotropic effect of a gene can be primary or secondary. With primary pleiotropy, a gene exhibits its multiple effects. With secondary pleiotropy, there is one primary phenotypic manifestation of a gene, followed by a stepwise process of secondary changes leading to multiple effects. With pleiotropy, a gene, acting on one main trait, can also change and modify the expression of other genes, and therefore the concept of modifier genes has been introduced. The latter enhance or weaken the development of traits encoded by the “main” gene. Indicators of the dependence of the functioning of hereditary inclinations on the characteristics of the genotype are penetrance and expressivity. When considering the effect of genes and their alleles, it is necessary to take into account the modifying influence of the environment in which the organism develops. This fluctuation of classes during splitting depending on environmental conditions is called penetrance - the strength of phenotypic manifestation. So, penetrance is the frequency of expression of a gene, the phenomenon of the appearance or absence of a trait in organisms of the same genotype. Penetrance varies significantly among both dominant and recessive genes. It can be complete, when the gene manifests itself in 100% of cases, or incomplete, when the gene does not manifest itself in all individuals containing it. Penetrance is measured by the percentage of organisms with a phenotypic trait from the total number of examined carriers of the corresponding alleles. If a gene completely determines phenotypic expression, regardless of the environment, then it has 100 percent penetrance. However, some dominant genes are expressed less regularly.

The multiple or pleiotropic effect of genes is associated with the stage of ontogenesis at which the corresponding alleles appear. The earlier the allele appears, the greater the pleiotropy effect.

Considering the pleiotropic effect of many genes, it can be assumed that some genes often act as modifiers of the action of other genes.

47. modern biotechnologies in animal husbandry. Application of breeding - gene value (research axes; transpl. Fruit).

Genotype and phenotype are concepts that teenagers become familiar with in last grades secondary school. But not everyone understands what these words mean. We can guess that this is some kind of classification of people's characteristics. What is the difference between these consonant names?

Human genotype

A genotype refers to all hereditary characteristics of a person, that is, a set of genes located on chromosomes. The genotype is formed depending on the inclinations and adaptation mechanisms of the individual. After all, every living organism is in certain conditions. Animals, birds, fish, protozoa and other types of living organisms adapt to the conditions where they live. So does a person living in the southern part Globe, can easily tolerate high air temperatures or too low temperatures due to skin color. Such adaptation mechanisms work not only relatively geographical location subject, but also other conditions; in a word, this is called a genotype.

What is a phenotype?

To know what genotype and phenotype are, you need to know the definition of these concepts. We have already dealt with the first concept, but what does the second mean? The phenotype includes all the properties and characteristics of an organism that it acquired during development. When a person is born, he already has his own set of genes that determine his adaptability to external conditions. But in the process of life, under the influence of internal and external factors, genes can mutate, change, so it appears qualitatively new structure characteristics of a person - phenotype.

The history of these concepts

What genotype and phenotype are can be understood by learning the history of the occurrence of these scientific terms. At the beginning of the twentieth century, the science of the structure of a living organism and biology was actively studied. We remember Charles Darwin's theory of evolution and the emergence of man. He was the first to put forward the Temporary hypothesis about the separation of cells in the body (gemmules), from which another individual could subsequently emerge, since these are germ cells. Thus, Darwin developed the theory of pangenesis.

41 years later, in 1909, the botanist Wilhelm Johansen, based on the concept of “genetics” already known in those years (introduced in 1906), introduced a new concept into the terminology of science - “gene”. The scientist replaced with it many words that were used by his colleagues, but which did not reflect the entire essence of the innate properties of a living organism. These are words such as “determinant”, “germ”, “hereditary factor”. During the same period, Johansen introduced the concept of “phenotype,” emphasizing the hereditary factor in the previous scientific term.

Human genotype and phenotype - what is the difference?

By highlighting two concepts about the properties and characteristics of a living organism, Johansen clearly defined the difference between them.

• Genes are passed on to offspring by an individual. An individual receives its phenotype during its life development.
• Genotype and phenotype also differ in that genes in a living being appear as a result of the combination of two sets of hereditary information. The phenotype appears on the basis of the genotype, undergoing various changes and mutations. These changes occur under the influence of external conditions of existence of a living organism.
• The genotype is determined by complex analysis The DNA and phenotype of an individual can be seen by analyzing the basic criteria of appearance.

It should be noted that living organisms have different level adaptability and sensitivity to the conditions around them. This determines how much the phenotype will be changed during life.

Differences between people by genotype and phenotype

Even though we belong to the same biological species, but we are very different from each other. There are no two identical people, the genotype and phenotype of each will be individual. This manifests itself if you place absolutely different people in equally unusual conditions for them, for example, sending an Eskimo to villages South Africa, and ask a Zimbabwean to live in the tundra. We will see that this experiment will not be crowned with success, since these two people are accustomed to living in their own geographical latitudes. The first difference between people in terms of geno- and phenotypic characteristics is adaptation to climatic and geographical factors.

The next difference is dictated by the historical-evolutionary factor. It lies in the fact that as a result of population migrations, wars, the culture of certain nationalities, their mixing, ethnic groups were formed that have their own religion, national characteristics and culture. Therefore, you can see clear differences between the style and way of life, for example, of a Slav and a Mongol.

Differences between people can also be based on social parameters. This takes into account the level of people’s culture, education, and social aspirations. It was not for nothing that there was such a thing as “blue blood,” which indicated that the genotype and phenotype of a nobleman and a commoner were significantly different.

The final criterion for differences between people is economic factor. Depending on the provision of a person, family and society, needs arise, and, consequently, differences between individuals.

There are two very important concepts in genetics. These are concepts genotype And phenotype. We already know that the hereditary constitution consists of large number various genes. The entire set of genes of a given organism is called its genotype , that is, the concept of genotype is identical to the concept of genetic constitution. Each person receives his own genotype (set of genes) at the moment of conception and carries it without any changes throughout his life. The activity of genes may change, but their composition remains unchanged.

From the concept genotype Another similar concept should be distinguished - genome. Genome is a set of genes characteristic of the haploid set of chromosomes of an individual of a given species. Unlike the genotype, the genome is a characteristic of a species, not an individual.
Phenotype represents any manifestations of the organism at every moment of its life. The phenotype includes appearance, And internal structure, and physiological reactions, and any forms of behavior observed at the current moment.

For example, the already mentioned blood groups of the AB0 system are an example of a phenotype at the physiological and biochemical level. Although at first glance it seems to many that the blood type is a genotype, since it is clearly determined by the action of genes and does not depend on the environment, it is only a manifestation of the action of genes, and therefore should be classified as a phenotype. Let us remember that representatives of blood groups A or B can have different genotypes (homozygous and heterozygous).

All behavioral manifestations are complex phenotypes. For example, the handwriting that distinguishes a given individual is his behavioral manifestation and also belongs to the category of phenotypes. If the blood type does not change throughout life, then handwriting undergoes significant changes as writing skills are trained.

If genotypes are inherited and remain unchanged throughout the life of the individual, then phenotypes for the most part are not inherited - they develop and are a consequence of our genotypes only to a certain extent, since environmental conditions play a large role in the formation of phenotypes.

The entire development process from a fertilized egg to an adult organism occurs not only under the continuous regulatory influence of the genotype, but also under the influence of many various conditions the environment in which the growing organism is located. Therefore, the extraordinary variability inherent in living organisms is due not only to the enormous diversity of genotypes arising from the recombination of genes and the mutation process, but is also largely explained by the fact that individual individuals develop in different environmental conditions.

For a long time there has been controversy about what is more important for the formation of an organism - the environment or the genetic constitution. Particularly heated debates flare up where it concerns human behavior, his psychological characteristics- temperament, mental abilities, personality traits. It is no coincidence that it was with the question of the nature of mental talent that research in the field of human genetics began. F. Galton was the first in a scientific treatise to put two concepts side by side, which in one form or another do not leave the pages scientific literature to the present day. These concepts are “nature and nurture”, that is, “the nature and conditions of upbringing”.

Geneticists, and behavioral geneticists in particular, are often accused of denying the role of the environment. However, such a reproach is completely unfounded. One of the main postulates of genetics is the thesis that phenotype is the result of the interaction of genotype and environment. In the process of this interaction, the diversity of phenotypic manifestations arises, which is characteristic of most human traits that belong to the category of quantitative and form a continuous series of variability.

What is Genotype and Phenotype

Genotype is kit genetic information, which is responsible for the structure of the body and gives it inherited traits. In other words, we can say that a genotype is the genetic code of an organism, which exists in the form of genetic data such as DNA or RNA. Phenotype is external physical manifestation organism, which can be observed visually without resorting to studies of the genetic code.

What is GENOTYPE and PHENOTYPE - definition in simple words.

In simple words, Genotype is internal encoded heritable information that is carried by all living beings. It's kind of general plan or a set of instructions for building a new organism, which specifies all the parameters of how the given organism should look and function. These instructions are transmitted in encoded form - genetic code. In turn, the genetic code is present in all cells of the body, and it is copied during cell division or reproduction, passing on hereditary information to offspring. The information contained in the genetic code is directly related to all aspects of the life of the cell and the organism as a whole. It is she who controls absolutely all processes, from the formation of protein macromolecules to the regulation of metabolism and.

In simple words, Phenotype is the appearance and behavior of a particular individual. In other words, it is the result of what an organism has become under the influence of the components of the genotype, the ratio of dominant alleles and the environment.

GENOTYPE and PHENOTYPE - how they differ.

Speaking of such two concepts as “genotype” and “phenotype”, first of all it should be noted that they are indeed closely related to each other, but have fundamental differences. The fact is that the term Genotype is applicable specifically to the genetic information contained in the gene code. The genotype can only be determined through biological tests and studies. In turn, the phenotype is the consequences of the genotype and other factors that can simply be seen.

If we talk about the differences quite simply, then:

• Genotype is a code (you can't just see him);
• Phenotype is the way the code manifests itself (you can observe: eye color, hair, height, behavior, etc.).