Basics of genetics. Selection and genetics: definitions, concepts, stages of evolution, development methods and application features Message on the topic of genetics, theoretical basis of selection

The modern period of development of selection begins with the formation of a new science - genetics. Genetics is a science that studies the heredity and variability of organisms. A very important contribution to elucidating the essence of heredity was made by G. Mendel (1822-1884), whose experiments in plant crossing form the basis of most modern research on heredity. A Czech by nationality, a monk of the Franciscan monastery in Brunn (now Brno), G. Mendel at the same time taught natural sciences at a real school and was very interested in gardening. For many years, he devoted all his free time to experiments in crossing various cultivated plants. As a result, patterns of transmission of traits to offspring were discovered. G. Mendel reported his results at a meeting of the “Society of Natural Scientists” in Brno, and then published them in 1866 in the scientific works of this Society. However, these provisions contradicted the existing ideas about heredity at that time and therefore received recognition 34 years after their rediscovery.

In 1900, three works appeared simultaneously, carried out by three geneticists: Hugo de Vries from Holland, K. Correns from Germany and E. Cermak from Austria. They confirmed the laws of heredity discovered by G. Mendel.

The published work of de Vries, Correns and Cermak is usually called the rediscovery of Mendel's laws and 1900 is considered the official date of the beginning of the existence of experimental genetics as an independent science.

Genetics as an independent science was separated from biology at the suggestion of the English scientist Bateson in 1907. He also suggested the name of the science – genetics.

Since the rediscovery of Mendel's laws, N.P. Dubinin (1986) distinguishes three stages in the development of genetics.

First stage - This is the era of classical genetics, which lasted from 1900 to 1930. This was the time of the creation of the gene theory and the chromosomal theory of heredity. The development of the doctrine of phenotype and genotype, the interaction of genes, the genetic principles of individual selection in breeding, and the doctrine of mobilizing the planet's genetic reserves for selection purposes were also of great importance. Some of the discoveries of this period deserve special mention.

The German biologist August Weismann (1834-1914) created a theory that in many ways anticipated the chromosomal theory of heredity.

Weisman's hypotheses about the meaning of reduction division. In addition, he distinguished between traits that are inherited and traits that are acquired under the influence of external conditions or exercise

A. Weisman tried to experimentally prove the non-heritability of mechanical damage (for generations he cut off her tails, but did not get tailless offspring).

Subsequently, A. Weisman’s general concept was refined taking into account cytological data and information about the role of the nucleus in the inheritance of characteristics. In general, he was the first to prove the impossibility of inheriting characteristics acquired during ontogenesis, and emphasized the autonomy of germ cells, and also showed the biological significance of the reduction in the number of chromosomes in meiosis as a mechanism for maintaining the constancy of the diploid chromosome set of the species and the basis of combinative variability.

In 1901, G. De Vries formulated a mutation theory that largely coincides with the theory of heterogenesis (1899) of the Russian botanist S. I. Korzhinsky (1861–1900). According to the mutation theory of Korzhinsky - De Vries, hereditary characteristics are not absolutely constant, but can change abruptly due to changes - mutation of their inclinations.

The most important milestone in the development of genetics - the creation of the chromosomal theory of heredity - is associated with the name of the American embryologist and geneticist Thomas Gent Morgan (1866–1945) and his school. Based on experiments with fruit flies - Drosophila melanogaster By the mid-20s of our century, Morgan formed the idea of the linear arrangement of genes in chromosomes and created the first version of the theory of the gene - the elementary carrier of hereditary information. The gene problem has become the central problem of genetics. It is currently being developed.

The doctrine of hereditary variability was continued in the works of the Soviet scientist Nikolai Ivanovich Vavilov (1887–1943), who formulated the law of homological series of hereditary variability in 1920. This law summarized a huge amount of material about the parallelism of variability of close genera and species, thus linking together systematics and genetics. The law was a major step towards the subsequent synthesis of genetics and evolutionary teaching. N.I. Vavilov also created the theory of genetic centers of cultivated plants, which greatly facilitated the search and introduction of the necessary plant genotypes.

During the same period, some other areas of genetics important for agriculture began to develop rapidly. These include works on the study of patterns of inheritance of quantitative traits (in particular, studies by the Swedish geneticist G. Nilsson-Ehle), on elucidation of hybrid power - heterosis (works of American geneticists E. East and D. Jones), on interspecific hybridization of fruit plants (I V. Michurin in Russia and L. Burbank in the USA), numerous studies devoted to the private genetics of various types of cultivated plants and domestic animals.

The formation of genetics in the USSR also belongs to this stage. In the post-October years, three genetic schools emerged, headed by prominent scientists: N.K. Koltsov (1872–1940) in Moscow, Yu.A. Filipchenko (1882–1930) and N.I. Vavilov (1887–1943) in Leningrad, who played important role in the development of genetics research.

Second phase, - This is the stage of neoclassicism in genetics, which lasted from 1930 to 1953. Start second stage can be associated with the discovery by O. Avery in 1944 of the substance of heredity - deoxyribonucleic acid (DNA).

This discovery symbolized the beginning of a new stage in genetics - the birth of molecular genetics, which formed the basis for a number of discoveries in biology of the 20th century.

During these years, the possibility of artificially causing changes in genes and chromosomes (experimental mutagenesis) was discovered; it was discovered that a gene is a complex system that can be divided into parts; the principles of population genetics and evolutionary genetics are substantiated; biochemical genetics was created, which showed the role of genes for all major biosyntheses in the cell and organism;

The achievements of this period primarily include artificial mutagenesis. The first evidence that mutations can be induced artificially was obtained in 1925 in the USSR by G. A. Nadson and G. S. Filippov in experiments on irradiation of lower fungi (yeast) with radium, and decisive evidence of the possibility of experimentally obtaining mutations was given in 1927 d. experiments of the American Meller on the effects of x-rays.

Another American biologist J. Stadler (1927) discovered similar effects in plants. Then it was discovered that ultraviolet rays can also cause mutations and that high temperature has the same ability, although to a weaker extent. Soon there was also information that mutations could be caused by chemicals. This direction gained wide scope thanks to the research of I. A. Rapoport in the USSR and S. Auerbach in Great Britain. Using the method of induced mutagenesis, Soviet scientists led by A. S. Serebrovsky (1892–1948) began studying the structure of the gene in Drosophila Melanogaster. In their studies (1929–1937), they were the first to show its complex structure.

At the same stage in the history of genetics, a direction arose and developed with the goal of studying genetic processes in evolution. Fundamental works in this area belonged to the Soviet scientist S. S. Chetverikov (1880–1959), the English geneticists R. Fisher and J. Haldane and the American geneticist S. Wright. S.S. Chetverikov and his collaborators carried out the first experimental studies of the genetic structure of natural populations on several species of Drosophila. They confirmed the importance of the mutation process in natural populations. Then these works were continued by N.P. Dubinin in the USSR and F. Dobzhansky in the USA.

At the turn of the 40s, J. Bill (born in 1903) and E. Tatum (1909–1975) laid the foundations of biochemical genetics.

Priority in deciphering the structure of the DNA molecule belongs to the American virologist James Dew Watson (born in 1928) and the English physicist Francis Crick (born in 1916), who published the structural model of this polymer in 1953.

From this moment, namely 1953, the third stage in the development of genetics begins - the era of synthetic genetics . This time is usually called the period of molecular genetics.

Third stage , which began with the construction of a DNA model, continued with the discovery of the genetic code in 1964. This period is characterized by numerous works on deciphering the structure of genomes. So, at the end of the 20th century, information appeared about the complete decoding of the genome of the Drosophila fly, scientists compiled a complete map of Arabidopsis or small mustard, and the human genome was deciphered.

Deciphering only individual sections of DNA already allows scientists to obtain transgenic plants, i.e. plants with introduced genes from other organisms. According to some sources, an area equal to Great Britain is sown with such plants. These are mainly corn, potatoes, and soybeans. Nowadays, genetics is divided into many complex areas. It is enough to note the achievements of genetic engineering in producing somatic and transgenic hybrids, the creation of the first map of the human genome (France, 1992; USA, 2000), the production of cloned sheep (Scotland, 1997), cloned piglets (USA, 2000), etc.

The beginning of the 21st century is called the post-genomic period and, apparently, will be marked by new discoveries in the field of genetics related to the cloning of living beings and the creation of new organisms based on genetic engineering mechanisms.

The methods accumulated to date make it possible to decipher the genomes of complex organisms much faster, as well as introduce new genes into them.

Major discoveries in the field of genetics:

1864 – Basic laws of genetics (G. Mendel)

1900 – G. Mendel’s laws were rediscovered ( G. de Vries, K. Correns, E. Cermak)

1900–1903 – Mutation theory (G.de Vries)

1910 – Chromosomal theory of heredity (T. Morgan, T. Boveri, W. Sutton)

1925–1938 – “one gene - one protein” (J. Bill, E. Tatum)

1929 – gene divisibility (A.S. Serebrov, N.P. Dubinin)

1925 – artificial mutations (G.A. Nadson, G.S. Filippov)

1944 – DNA – the carrier of hereditary information (O. Avery, K. McLeod)

1953 – DNA structural model (J. Watson, F. Crick)

1961 – genetic code (M. Nirenberg, R. Holley, G. Khorana)

1961 – operon principle of gene organization and regulation of gene activity in bacteria (F. Jacob, J. Monod)

1959 – gene synthesis (G. Khorana )

1974–1975 – methods of genetic engineering ( K. Murray, N. Murray, W. Benton, R. Davis, E. Southern, M. Granstein, D. Hognes)

1978–2000 – deciphering genomes (F. Blatner, R. Clayton, M. Adams, etc.)

Genetics methods

HYBRIDOLOGICAL – p An analysis is made of the patterns of inheritance of individual characteristics and properties of organisms during sexual reproduction, as well as an analysis of the variability of genes and their combinatorics (developed by G. Mendel).

CYTOLOGICAL - with Using optical and electron microscopes, the material basis of heredity is studied at the cellular and subcellular levels (chromosomes, DNA).

CYTOGENETIC – with the integration of hybridological and cytological methods ensures the study of the karyotype, changes in the structure and number of chromosomes.

POPULATION-STATISTICAL – o It is based on determining the frequency of occurrence of various genes in a population, which makes it possible to calculate the number of heterozygous organisms and thus predict the number of individuals with a pathological (mutant) manifestation of the gene’s action.

BIOCHEMICAL- metabolic disorders (proteins, fats, carbohydrates, minerals) resulting from gene mutations are studied.

MATHEMATICAL – n A quantitative accounting of the inheritance of traits is carried out.

GENEALOGICAL – Expressed in the compilation of pedigrees. Allows you to establish the type and nature of inheritance of traits.

ONTOGENETIC – Allows you to trace the action of genes in the process of individual development; in combination with a biochemical method, it makes it possible to establish the presence of recessive genes in a heterozygous state by phenotype.

Selection is the science of creating new and improving existing animal breeds, plant varieties and strains of microorganisms. The theoretical basis of selection is genetics.

Selection tasks :

Increasing the productivity of plants, animals and microorganisms

Breeding new breeds, varieties, strains

Ensuring maximum production with minimum costs

To solve these problems it is necessary:

Knowledge of the patterns of inheritance of traits

Study of hereditary variability

Study of modification variability (the influence of the environment on the development of traits)

Study of varietal, species and generic diversity of crops

Development of artificial selection strategies and methods

Breeds of animals, varieties of plants and strains of microorganisms are populations of organisms artificially created by man, with a characteristic set of traits fixed hereditarily (productivity). Strains - the offspring of one cell, a pure culture, but at the same time different strains can be obtained from one cell.

Often cultivated plants and domestic animals cannot live without humans, since as a result of selection, organisms have been instilled with traits that are beneficial to humans, but harmful to the organisms themselves.

In Russia, the founder of selection is considered Nikolay Vavilov .

Installed 8 centers of origin cultivated plants, because during expeditions he studied their diversity and wild ancestors in different places around the globe.

Formulated law of homological series heredity and variability: species and genera that are genetically close are characterized by similar series of genetic variability. Knowing what forms of variability are observed in one species, one can predict the discovery of similar forms in a related species. This is because related species evolved from a common ancestor through natural selection. That is, the descendants inherited approximately the same set of genes from him and the resulting mutations should be similar.

The law applies to plants and animals: albinism and lack of feathers in birds; albinism and hairlessness in mammals. In plants, parallelism is observed in the following characters: bare and filmy grains, awned and awnless ears.

For breeding and agriculture, this makes it possible to find in related species a characteristic feature that is absent in one, but present in others. Medicine receives material for its research, since it is possible to study human diseases using animals with homologous diseases. For example, diabetes mellitus in rats, congenital deafness in mice, cataracts in dogs, etc.

Hybridization

The process of obtaining hybrids is based on combining the genetic material of different cells and organisms. Hybrids can be obtained during the sexual process by combining somatic cells. Hybridization: interspecific and intraspecific (related and unrelated)

1) Inbreeding - inbreeding of organisms with common ancestors. Characteristic of self-pollinating plants and hermaphroditic animals.

Hard - crossing close relatives: mother and son, brother and sister

Soft - crossing of related organisms in 4 and subsequent generations

With each generation, the homozygosity of hybrids increases, and since many harmful mutations are in recessive genes; they manifest themselves in a homozygous state. The consequence of inbreeding is the weakening and degeneration of descendants. Inbreeding produces clean lines , rare desirable characteristics are fixed.

2) Outbreeding - unrelated crossing of organisms, without family ties over the previous 6 generations. This is the crossing of representatives of the same species, but different lines, varieties, breeds. They are used to combine the valuable properties of various lines, to increase the viability of breed or varietal lines, which helps prevent their degeneration.

Heterosis - a phenomenon in which the first generation of hybrids has increased productivity and viability compared to the parent forms.

Full manifestation of heterosis is observed only in the first generation, since most alleles become heterozygous. Then they gradually pass into a homozygous state and the effect of heterosis weakens. It is used in agriculture, as clean lines are always maintained in plant breeding. Heterosis of plants can be reproductive, somatic and adaptive.

4) Distant or interspecific hybridization - crossing two individuals of different species. Used to combine valuable qualities of individuals of different species. This is how hybrids were obtained: wheat and wheatgrass, rye and wheat = triticale, cherry and bird cherry = ceropadus, beluga and sterlet = bester, stallion and donkey = hinny, ferret and mink = honorik, hare hare and white hare = cuff.

Wild argali sheep and fine-wool merino sheep = arharomerinos

Mare and donkey = mule, hardy, strong, sterile, with a long lifespan and increased vitality.

Problem - infertility interspecific hybrids. This occurs due to the fact that different species have different numbers and structure of chromosomes, therefore the conjugation and process of chromosome segregation during meiosis is disrupted.

Overcoming infertility in animal hybrids is especially difficult. In 1924 Karpechenko created a cabbage-radish hybrid and for the first time overcame infertility using the method polyplodization . He crossed radish and cabbage (2 n -18; n -9 HR-m). But during meiosis, the chromosomes did not conjugate or separate; the hybrids were sterile. Then, using colchicine, which blocks the formation of spindle microtubules, Karpechenko doubled the chromosome set of hybrids to tetraploid (4 n -36, 2 n -18). As a result, conjugation, the formation of gametes and restoration of fertility became possible.

It has become possible to produce hybrids in animals using cell engineering.

Selection

Artificial selection - creation of new breeds and varieties through the systematic preservation and reproduction of individuals with certain characteristics. At first, selection was carried out unconsciously: man carried it out from the beginning of the domestication of animals. Modern selection is carried out consciously, based on knowledge of selection and genetics, that is, the laws of heredity and variability.

The theoretical foundations were put forward by Charles Darwin. He proved that varieties and breeds have one common ancestor and are not independent species. Man formed varieties and breeds according to his own interests, often to the detriment of the viability of animals.

- massive aimed at preserving the group. Used primarily for microorganisms and cross-pollinated plants. Selection is carried out according to phenotype , thereby the desired trait is increasingly developed.

- individual aimed at preserving individuals. It is used for self-pollinating plants (obtaining pure lines) and animals. Since the period for producing offspring in animals is quite long, selection is carried out according to genotype , individual individuals are left for reproduction.

Mutagenesis

Mutagenesis is the production of mutations using physical and chemical agents. For example method polyplodization , the effect of which is achieved by exposure to the poison colchicine, which destroys the filaments of the spindle.

Features of selection

1) Plants

Sexual and asexual reproduction is typical; mass selection based on phenotype is used. Various forms of hybridization. Polyploidy is used to increase the resistance of varieties and overcome the sterility of hybrids.

Michurin – mentor method : directed influence of the parent plant on the properties of the young hybrid after grafting.

Features of animal selection

Animals reproduce only sexually, which significantly limits selection methods. The main methods are individual selection and various forms of hybridization. In agriculture, the phenomenon of heterosis and artificial insemination are used.

Astaurov - silkworm by polyplodization.

Ivanov – Ukrainian white steppe pig by interspecific hybridization

Features of microorganism selection

The bacterial genome is haploid, represented by one circular DNA molecule, so any mutations appear already in the first generation. However, a very high reproduction rate facilitates the search for mutants. The main methods are experimental artificial mutagenesis and selection of the most productive strains. This is how a strain of the penicillium fungus was obtained, the productivity of which was increased several times.

Modern additional breeding methods .

1. Artificial insemination.

2. Hormonal super-ovulation.

3. Embryo transplantation.

Darwin's views

Darwin studied methods for breeding new breeds and established stages: the breeder selects individuals with the characteristics he needs; receives offspring from them; selects individuals in which the desired trait is better expressed. After several generations, the trait is fixed, becomes stable, and a new breed or variety is formed.
Thus, the selection is based on the following factors:

1. The initial diversity of an individual, that is, their natural variability.

2. Transmission of traits by inheritance.

3. Artificial selection.

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Genetics is a science that studies two properties of living organisms - heredity and variability. Advances in genetics are of great importance for medicine, agriculture and biology.

Heredity

Heredity is understood as the ability of organisms to pass on their characteristics and properties to their offspring. It is thanks to heredity that this or that breed or species of animal or plant variety is preserved for many generations.

Variability

Variability is the property of organisms to acquire new characteristics that differ from their parents. If these characteristics are fixed in subsequent generations, then they speak of hereditary variability.

Rice. 1. Modification variability.

Variability determines the variety of properties and external data within one species.

The material carrier of information about the properties of a cell is DNA. It is part of chromosomes - structures of the cell nucleus that store hereditary information.

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According to modern views of heredity, differences between species and organisms within a species are determined by differences in the proteins from which the organisms are built.

Information about the structure of a particular protein is contained in the gene. A gene is a section of a DNA molecule.

Rice. 2. Gen.

Information is read from genes, which is then implemented in the creation of protein molecules.

Genotype

Each type of organism is characterized by a certain number and shape of chromosomes - its genotype. For example, a person has 23 pairs of chromosomes in his genotype. Half of the chromosomes come from the father and half from the mother.

Rice. 3. Chromosome sets.

Sex cells contain a half or haploid set of chromosomes (n), and somatic cells contain a diploid (2n) or double set.

Phenotype

A trait encoded in a gene may or may not appear, depending on the interaction of genes and the characteristics of environmental conditions. The most common type of interaction between genes is the suppression of the action of one gene by another. All manifested signs form the phenotype of the organism.

Selection

Selection is closely related to genetics. She is engaged in the creation of new and targeted changes in existing plant varieties and animal breeds.

The foundations of genetics and selection are knowledge about the patterns of inheritance of traits and their manifestation in the phenotype.

Many high-yielding varieties of cultivated plants were created by breeders by multiplying the number of chromosomes (3n, 4n, etc.). Such crops are called polyploids.

What have we learned?

Genetics studies two important properties of living organisms: the ability to transmit properties from generation to generation; the ability to acquire new qualities. A separate feature of an organism is a protein, information about the structure of which is encrypted in a gene - a section of a DNA molecule. The genetic foundations of genetics are the theoretical basis for versatile biological and medical research and increasing agricultural productivity.

Humanity has long been engaged in the selection of plant crops and animals suitable to meet the needs of the population. This knowledge is combined into the science of selection. Genetics, in turn, provides the basis for more careful selection and breeding of new varieties and breeds that have special qualities. In the article we will consider a description of these two sciences and the features of their application.

What is genetics?

Gene science is a discipline that studies the process of transmission of hereditary information and the variability of organisms through generations. Genetics is the theoretical basis of selection, the concept of which is described below.

The tasks of science include:

Study of the mechanism of storage and transmission of information from ancestors to descendants.
Studying the implementation of such information in the process of individual development of the organism, taking into account the influence of the environment.
Study of the causes and mechanisms of variability in living organisms.
Determination of the relationship between selection, variability and heredity as factors in the development of the organic world.

Science is also involved in solving practical problems, which shows the importance of genetics for selection:

Determination of selection efficiency and selection of the most appropriate types of hybridization.
Control of the development of hereditary factors in order to improve the object to obtain more significant qualities.
Obtaining hereditarily modified forms artificially.
Development of measures aimed at protecting the environment, for example, from the influence of mutagens and pests.
Fight against hereditary pathologies.
Achieving progress in creating new breeding methods.
Search for other methods of genetic engineering.

The objects of science are: bacteria, viruses, humans, animals, plants and fungi.

Basic concepts used in science:

Heredity is the property of preservation and transmission to descendants inherent in all living organisms, which cannot be taken away.
A gene is a part of a DNA molecule that is responsible for a certain quality of an organism.
Variability is the ability of a living organism to acquire new qualities and lose old ones in the process of ontogenesis.
Genotype is a set of genes, the hereditary basis of an organism.
Phenotype is a set of qualities that an organism acquires in the process of individual development.

Stages of genetic development

The development of genetics and selection took place in several stages. Let's consider the periods of formation of the science of genes:

Methods of genetic science

Genetics, as the theoretical basis of selection, uses certain methods in its research.

These include:

Hybridization method. It is based on crossing species with a pure line that differ in one (maximum several) characteristics. The goal is to obtain hybrid generations, which allows one to analyze the nature of inheritance of traits and count on obtaining offspring with the necessary qualities.
Genealogy method. It is based on the analysis of the family tree, which makes it possible to trace the transmission of genetic information through generations, adaptability to diseases, and also to characterize the value of an individual.
Twin method. It is based on a comparison of monozygotic individuals and is used when it is necessary to establish the degree of influence of paratypic factors while ignoring differences in genetics.
The cytogenetic method is based on analyzing the nucleus and intracellular components, comparing the results obtained with the norm according to the following parameters: the number of chromosomes, the number of their arms and structural features.
is based on the study of the functions and structure of certain molecules. For example, the use of various enzymes is used in biotechnology and genetic engineering.
The biophysical method is based on the study of polymorphism of plasma proteins, such as milk or blood, which provides information about the diversity of populations.
The monosome method uses somatic cell hybridization as a basis.
The phenogenetic method is based on the study of the influence of genetic and paratypic factors on the development of the qualities of an organism.
The population statistical method is based on the use of mathematical analysis in biology, which allows one to analyze quantitative characteristics: calculation of average values, indicators of variability, statistical errors, correlation and others. The use of the Hardy-Weinberg law helps in analyzing the genetic structure of the population, the level of distribution of anomalies, and also to trace the variability of the population when applying various selection options.

What is selection?

Selection is the science that studies methods for creating new varieties and hybrids of plants, as well as animal breeds. selection is genetics.

The goal of science is to improve the qualities of the body or obtain in it the properties necessary for a person by influencing heredity. New species of organisms cannot be created through selection. Selection can be considered a form of evolution in which artificial selection is present. Thanks to it, humanity is provided with food.

The main tasks of science:

qualitative improvement of body characteristics;
increasing productivity and yield;
increasing the resistance of organisms to diseases, pests, and changes in climatic conditions.

A special feature is the complexity of science. It is closely related to anatomy, physiology, morphology, systematics, ecology, immunology, biochemistry, phytopathology, plant growing, animal husbandry and many other sciences. Knowledge of fertilization, pollination, histology, embryology and molecular biology is significant.

The achievements of modern selection make it possible to control the heredity and variability of living organisms. The importance of genetics for breeding and medicine is reflected in the targeted control of the continuity of qualities and the possibility of obtaining hybrids of plants and animals to meet human needs.

Stages of selection development

For a long time, man has been engaged in the breeding and selection of plants and animals for agricultural purposes. But such work was based on observation and intuition. The development of selection and genetics took place almost simultaneously. Let's consider the stages of selection development:

During the period of development of crop production and livestock breeding, selection began to be massive, and the emergence of capitalism led to selective work at the industrial level.
At the end of the 19th century, the German scientist F. Achard conducted a study and instilled in sugar beets the quality of increasing yield. English breeders P. Shireff and F. Galleta studied wheat varieties. In Russia, the Poltava Experimental Field was created, where studies of the varietal composition of wheat took place.
Selection as a science began to develop in 1903, when a breeding station was organized at the Moscow Agricultural Institute.
By the middle of the 20th century, the following discoveries were made: the law of hereditary variability, the theory of centers of origin of plants for cultural purposes, ecological and geographical principles of selection, knowledge was gained about the source material of plants and their immunity. The All-Union Institute of Applied Botany and New Crops was created under the leadership of N. I. Vavilov.
Research from the end of the 20th century to the present day has been comprehensive; selection closely interacts with other sciences, especially with genetics. Hybrids with high agroecological adaptation were created. Modern research pays attention to obtaining high productivity and resistance to biotic and abiotic stressors in hybrids.

Breeding methods

Genetics examines the patterns of transmission of hereditary information and ways to control such a process. Breeding uses knowledge gained from genetics and uses other methods to evaluate organisms.

The main ones are:

Selection method. Selection uses natural and artificial (unconscious or methodical) selection. A specific organism (individual selection) or a group of them can also be selected. Determination of the type of selection is based on the characteristics of the reproduction of animals and plants.
Hybridization allows you to obtain new genotypes. The method distinguishes intraspecific (crossing occurs within one species) and interspecific hybridization (crossing of different species). Inbreeding allows you to consolidate hereditary properties while reducing the viability of the organism. If outbreeding is carried out in the second or subsequent generations, the breeder receives high-yielding and persistent hybrids. It has been established that with distant crossing the offspring are infertile. Here, the importance of genetics for selection is expressed in the possibility of studying genes and their influence on the fertility of organisms.
Polyploidy is the process of increasing chromosome sets, which makes it possible to achieve fertility in infertile hybrids. It has been noted that some cultivated plants after polyploidy have a higher birth rate than their related species.
Induced mutagenesis is an artificially induced process of mutation of an organism after treatment with a mutagen. After the mutation is completed, the breeder receives information about the influence of the factor on the organism and its acquisition of new qualities.
Cellular engineering is designed to construct new types of cells through culture, reconstruction, and hybridization.
Genetic engineering makes it possible to isolate and study genes, and manipulate them in order to improve the qualities of organisms and breed new species.

Plants

In the process of studying the growth, development and identification of beneficial properties of plants, genetics and selection are closely interrelated. Genetics in the field of analysis of plant life deals with the study of the characteristics of their development and genes that ensure the normal formation and functioning of the body.

Science studies the following areas:

Development of one specific organism.
Control of plant signaling systems.
Gene expression.
Mechanisms of interaction between plant cells and tissues.

Selection, in turn, ensures the creation of new or improvement of the qualities of existing plant species based on knowledge obtained through genetics. Science is studied and successfully used not only by farmers and gardeners, but also by breeders in research organizations.

The use of genetic achievements in breeding and seed production makes it possible to instill new qualities in plants that can be useful in various spheres of human life, for example in medicine or cooking. Also, knowledge about genetic characteristics allows us to obtain new varieties of crops that can grow in different climatic conditions.

Thanks to genetics, breeding uses the method of crossing and individual selection. The development of gene science allows the use of methods such as polyploidy, heterosis, experimental mutagenesis, chromosomal and genetic engineering in breeding.

Animal world

Animal breeding and genetics are branches of science that study the developmental characteristics of representatives of the animal world. Thanks to genetics, a person gains knowledge about heredity, genetic characteristics and variability of the body. And selection makes it possible to select for use only those animals whose qualities are necessary for humans.

For a long time, people have been selecting animals that, for example, are more suitable for use in agriculture or hunting. Economic traits and exterior are of great importance for selection. Thus, farm animals are assessed by the appearance and quality of their offspring.

The use of genetic knowledge in breeding makes it possible to control the offspring of animals and their necessary qualities:

resistance to viruses;
increase in milk yield;
individual size and build;
climate tolerance;
fertility;
gender of the offspring;
elimination of hereditary disorders in descendants.

Animal selection has become widespread not only in order to satisfy the primary needs of humans for nutrition. Today you can see many artificially bred domestic animal breeds, as well as rodents and fish, such as guppies. Selection and genetics in animal husbandry use the following methods: hybridization, artificial insemination, experimental mutagenesis.

Breeders and geneticists are often faced with the problem of non-crossing of species among the first generation of hybrids and a significant reduction in the fertility of offspring. Modern scientists are actively addressing such questions. The main objective of scientific work is to study the patterns of compatibility of gametes, the fetus and the mother’s body at the genetic level.

Microorganisms

Modern knowledge about selection and genetics makes it possible to meet human needs for valuable food products, which are mainly obtained from animal husbandry. But other objects of nature also attract the attention of scientists - microorganisms. Science has long believed that DNA is an individual trait and cannot be transferred to another organism. But research has shown that bacterial DNA can be successfully introduced into plant chromosomes. Thanks to this process, the qualities inherent in the bacteria or virus take root in another organism. The influence of genetic information of viruses on human cells has also long been known.

The study of genetics and selection of microorganisms is carried out in a shorter period of time compared to crop production and animal husbandry. This is explained by the rapid reproduction and change of generations of microorganisms. Modern methods of selection and genetics - the use of mutagens and hybridization - have made it possible to create microorganisms with new properties:

mutants of microorganisms are capable of supersynthesis of amino acids and increased formation of vitamins and provitamins;
mutants of nitrogen-fixing bacteria can significantly accelerate plant growth;
yeast organisms have been bred - unicellular fungi and many others.

Breeders and geneticists use the following mutagens:

ultraviolet;
ionizing radiation;
ethylenimine;
nitrosomethylurea;
use of nitrates;
acridine paints.

For mutation to be effective, frequent treatments of the microorganism with small doses of mutagen are used.

Medicine and biotechnology

What is common in the meaning of genetics for breeding and medicine is that in both cases science makes it possible to study the heredity of organisms and the immunity they exhibit. Such knowledge is important for combating pathogens.

The study of genetics in the field of medicine allows you to:

prevent the birth of children with genetic disorders;
carry out prevention and treatment of hereditary pathologies;
study the influence of the environment on heredity.

The following methods are used for this:

genealogical - the study of the family tree;
twin - comparison of a twin pair;
cytogenetic - study of chromosomes;
biochemical - allows you to identify mutant alleys in DNA;
dermatoglyphic - analysis of skin patterns;
modeling and others.

Modern research has identified approximately 2 thousand diseases that are inherited. These are mainly mental disorders. The study of genetics and selection of microorganisms can reduce the incidence of disease among the population.

Advances in genetics and selection in biotechnology make it possible to use biological systems (prokaryotes, fungi and algae) in science, industrial production, medicine, and agriculture. Knowledge about genetics provides new opportunities for the development of such technologies: energy- and resource-saving, waste-free, knowledge-intensive, safe. The following methods are used in biotechnology: cellular and chromosomal selection, genetic engineering.

Genetics and selection are sciences that are inextricably linked. Breeding work largely depends on the genetic diversity of the initial number of organisms. It is these sciences that provide knowledge for the development of agriculture, medicine, industry and other spheres of human life.

Date of________

Lesson No. 61 Topic: Genetics as the scientific basis for the selection of organisms. Source material for selection.

Lesson Objectives: Reveal the role of the geneticist in breeding. The role of theoretical knowledge in practice.

Career guidance for students in agricultural professions needed in the region. Educational institutions in our area.

Equipment: Images of varieties of domestic plants and animal breeds

During the classes

I . Organizing time :

II .Checking the assimilation of the material and activating knowledge on the previous topic:Repetition.

Match the term to the definition.

Selection is the science of breeding new and improving existing old varieties of plants, animal breeds and strains of microorganisms with properties necessary for humans.
A variety is a plant population artificially created by man, which is characterized by a certain gene pool, hereditarily fixed morphological and physiological characteristics, and a certain level and nature of productivity.
A breed is a population of animals artificially created by man, which is characterized by a certain gene pool, hereditarily fixed morphological and physiological characteristics, and a certain level and nature of productivity.
Strain is a population of microorganisms artificially created by man, which is characterized by a certain gene pool, hereditarily fixed morphological and physiological characteristics, and a certain level and nature of productivity.

2. What are the main objectives of selection as a science?
Increasing the productivity of plant varieties, animal breeds and strains of microorganisms;
Studying the diversity of plant varieties, animal breeds and strains of microorganisms;
Analysis of patterns of hereditary variability during hybridization and mutation process;
Study of the role of the environment in the development of characteristics and properties of organisms;
Development of artificial selection systems that contribute to the strengthening and consolidation of traits useful for humans in organisms with different types of reproduction;
Creation of varieties and breeds resistant to diseases and climatic conditions;
Obtaining varieties, breeds and strains suitable for mechanized industrial cultivation and breeding.

III . Learning new material :

What is the theoretical basis of selection?
The theoretical basis of selection is genetics. It also uses advances in the theory of evolution, molecular biology, biochemistry and other biological sciences.

Group work (12-15 min)

Group 1 - Basic genetic laws and selection.

Group 2 - What is the starting material for selection? Main types and methods of obtaining starting material.

Exchange of information - 5 minutes

Additional material.

Breeding work begins with the selection of material, on which its success primarily depends. The source material in breeding is the cultivated and wild forms of plants used for breeding new varieties, cultivated and indigenous species of animals for breeding new breeds.

The starting material is used:

Forms and varieties of plants found in nature

Plant forms created through the selection process

There are various breed groups in livestock farming.

Currently, there are about 3,000 breeds of farm animals:

Pigs-203

Horses -250

Rabbits-60

Oleney-12

Main types and methods of obtaining starting material:

1. Natural populations

2. Hybrid populations