The message of genetics is the theoretical basis of breeding briefly. Genetics as the theoretical basis of Selection. What is the theoretical basis of selection

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 property of organisms to transmit their characteristics and properties to offspring. It is thanks to heredity that one or another breed and type of animal, and variety of plants are preserved in many generations.

Variability

Variability is the property of organisms to acquire new traits that are different from the parent ones. If these signs 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 the same species.

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

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 the genotype. Half of the chromosomes are from the father and half from the mother.

Rice. 3. Chromosomal 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 manifest itself, 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 the manifested signs form the phenotype of the organism.

Selection

Selection is closely related to genetics. It is engaged in the creation of new and purposeful changes in existing varieties of plants 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 are created by breeders by multiplying the number of chromosomes (3n, 4n, etc.). Such cultures are called polyploids.

What have we learned?

Genetics studies two important properties of living organisms: the ability to transfer properties from generation to generation; the ability to acquire new qualities. A separate sign 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.

Selection is the science of creating new and improving existing breeds of animals, plant varieties, strains of microorganisms. Selection is based on methods such as hybridization and selection. The theoretical basis of selection is genetics. The development of selection should be based on the laws of genetics as a science of heredity and variability, since the properties of living organisms are determined by their genotype and are subject to hereditary and modification variability. It is genetics that paves the way effective management heredity and variability of organisms. At the same time, selection is also based on the achievements of other sciences:

taxonomy and geography of plants and animals,
cytology,
embryology,
biology of individual development,
molecular biology,
physiology and biochemistry.

The rapid development of these areas of natural science opens up completely new perspectives. Already today, genetics has reached the level of purposeful design of organisms with the desired features and properties. Genetics plays a decisive role in solving almost all breeding problems. It helps rationally, on the basis of the laws of heredity and variability, to plan the selection process, taking into account the characteristics of the inheritance of each specific trait.

To successfully solve the problems facing selection, Academician N.I. Vavilov emphasized the meaning:

study of varietal, species and generic diversity of crops;
study of hereditary variability;
the influence of the environment on the development of traits of interest to the breeder;
knowledge of the patterns of inheritance of traits during hybridization;
features of the selection process for self- or cross-pollinators;
artificial selection strategies.

Breeds, varieties, strains- populations of organisms artificially created by man with hereditarily fixed features:

productivity
morphological,
physiological signs.

Each animal breed, plant variety, strain of microorganisms is adapted to certain conditions, therefore, in each zone of our country there are specialized variety testing stations and breeding farms for comparing and testing new varieties and breeds. Selection work begins with the selection of source material, which can be used as cultivated and wild forms of plants.

In modern breeding, the following main types and methods of obtaining the source material are used.

natural populations. This type of source material includes wild forms, local varieties of cultivated plants, populations and accessions presented in the VIR world collection of agricultural plants.

hybrid populations, created as a result of crossing varieties and forms within the same species (intraspecific) and obtained as a result of crossing different species and genera of plants (interspecific and intergeneric).

Self-pollinated lines (incubation lines). In cross-pollinating plants, an important source of starting material is self-pollinated lines obtained by repeated forced self-pollination. The best lines are crossed with each other or with varieties, and the resulting seeds are used for one year to grow heterotic hybrids. Hybrids created on the basis of self-pollinated lines, unlike conventional hybrid varieties, need reproduce annually.

Artificial mutations and polyploid forms. This type of source material is obtained by exposing plants to various types of radiation, temperature, chemicals and other mutagens.

At the All-Union Institute of Plant Industry N.I. Vavilov collected a collection of varieties of cultivated plants and their wild ancestors from all over the globe, which is currently being replenished and is the basis for work on the selection of any crop. The richest in the number of cultures are the ancient centers of civilization. It is there that the earliest culture of agriculture is carried out, artificial selection and plant breeding are carried out for a longer time.

Classical methods of plant breeding were and still are hybridization and selection. There are two main forms of artificial selection: mass and individual.

Mass selection used in breeding cross-pollinated plants (rye, corn, sunflower). In this case, the variety is a population of heterozygous individuals, and each seed has a unique genotype. With the help of mass selection, varietal qualities are preserved and improved, but the selection results are unstable due to random cross-pollination.

Individual selection used in the selection of self-pollinated plants (wheat, barley, peas). In this case, the offspring retains the characteristics of the parental form, is homozygous and is called clean line. A pure line is the offspring of one homozygous self-pollinated individual. Since mutation processes are constantly occurring, there are practically no absolutely homozygous individuals in nature.

Natural selection. This type of selection plays a decisive role in selection. A complex of factors acts on any plant during its life. environment, and it must be resistant to pests and diseases, adapted to a certain temperature and water regime.

Hybridization- the process of formation or production of hybrids, which is based on the combination of the genetic material of different cells in one cell. It can be carried out within the same species (intraspecific hybridization) and between different systematic groups (distant hybridization, in which different genomes are combined). The first generation of hybrids is often characterized by heterosis, which is expressed in better adaptability, greater fecundity and viability of organisms. With distant hybridization, hybrids are often sterile. Most common in plant breeding method of hybridization of forms or varieties within the same species. Most modern varieties of agricultural plants have been created using this method.

distant hybridization- a more complex and time-consuming method of obtaining hybrids. The main obstacle to obtaining distant hybrids is the incompatibility of germ cells of crossed pairs and the sterility of hybrids of the first and subsequent generations. Distant hybridization is the crossing of plants belonging to different species. Distant hybrids are usually sterile, as they are disturbed meiosis(two haploid sets of chromosomes from different species cannot conjugate) and therefore no gametes are formed.

heterosis("hybrid strength") - a phenomenon in which hybrids surpass parental forms in a number of characteristics and properties. Heterosis is typical for hybrids of the first generation, the first hybrid generation gives an increase in yield up to 30%. In subsequent generations, its effect weakens and disappears. The effect of heterosis is explained by two main hypotheses. Dominance hypothesis suggests that the effect of heterosis depends on the number of dominant genes in the homozygous or heterozygous state. The more genes in the genotype in the dominant state, the greater the effect of heterosis.

	♀AAbbCCdd		♂aaBBccDD
	AaBbCcDd

Overdominance hypothesis explains the phenomenon of heterosis by the effect of overdominance. overdominance- type of interaction allelic genes, in which heterozygotes are superior in their characteristics (in weight and productivity) to the corresponding homozygotes. Starting from the second generation, heterosis fades, as part of the genes passes into the homozygous state.

cross pollination self-pollinators makes it possible to combine the properties of different varieties. For example, when breeding wheat, proceed as follows. Anthers are removed from the flowers of a plant of one variety, a plant of another variety is placed next to it in a vessel with water, and plants of two varieties are covered with a common insulator. As a result, hybrid seeds are obtained that combine the traits of different varieties that the breeder needs.

Method for obtaining polyploids. Polyploid plants have a larger mass of vegetative organs, larger fruits and seeds. Many crops are natural polyploids: wheat, potatoes, varieties of polyploid buckwheat, sugar beets have been bred. Species in which the same genome is multiply multiplied are called autopolyploids. The classic method for obtaining polyploids is the treatment of seedlings with colchicine. This substance blocks the formation of spindle microtubules during mitosis, the number of chromosomes doubles in the cells, and the cells become tetraploid.

Use of somatic mutations. Somatic mutations are used to select vegetatively propagating plants. This was used in his work by I.V. Michurin. By vegetative propagation, a beneficial somatic mutation can be maintained. In addition, only with the help of vegetative propagation, the properties of many varieties of fruit and berry crops are preserved.

experimental mutagenesis. It is based on the discovery of the impact of various radiations to obtain mutations and on the use of chemical mutagens. Mutagens allow you to get a wide range of different mutations. Now more than a thousand varieties have been created in the world, leading a pedigree from individual mutant plants obtained after exposure to mutagens.

Plant breeding methods proposed by I.V. Michurin. Using the method of mentor I.V. Michurin sought to change the properties of the hybrid in the right direction. For example, if it was necessary to improve the taste of a hybrid, cuttings from a parent organism that had good taste were grafted into its crown, or a hybrid plant was grafted onto a rootstock, in the direction of which it was necessary to change the quality of the hybrid. I.V. Michurin pointed to the possibility of controlling the dominance of certain traits during the development of a hybrid. For this, in the early stages of development, it is necessary to influence certain external factors. For example, if hybrids are grown in open ground, their frost resistance increases on poor soils.

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

Selection tasks :

Increasing the productivity of plants, animals and microorganisms

In the breeding of new breeds, varieties, strains

О Ensuring maximum production at minimum cost

To solve these problems it is necessary:

Knowledge of the patterns of inheritance of traits

The study of hereditary variability

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

The study of varietal, species and generic diversity of crops

Development of strategies and methods of artificial selection

Animal breeds, plant varieties and strains of microorganisms are populations of organisms artificially created by man, with a characteristic set of traits fixed hereditarily (productivity). Strains - progeny of one cell, pure culture, but different strains can be obtained from one cell.

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

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

Installed 8 centers of origin cultivated plants, as during the expeditions he studied their diversity and wild ancestors in different parts of the world.

formulated law homologous series heredity and variability: species and genera genetically close are characterized by similar rows genetic variability. Knowing what forms of variability are observed in one species, one can foresee the discovery of similar forms in a related species. This is because related species descended from a common ancestor during natural selection. That is, the descendants inherited from him approximately the same set of genes 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 terms of features: bare and filmy grain, spinous and awnless ear.

For breeding and agriculture, this makes it possible to find in related species feature, which is absent from one, but is 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 - closely related crossing of organisms, with common ancestors. It is typical for self-pollinating plants and hermaphroditic animals.

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

Soft - crossing 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 appear in the homozygous state. The consequence of inbreeding is the weakening and degeneration of offspring. Through inbreeding, clean lines , rare desirable features are fixed.

2) Outbreeding - unrelated crossing of organisms, without family ties for 6 previous generations. This is a crossing of representatives of the same species, but different lines, varieties, breeds. It is used to combine the valuable properties of various lines, to increase the viability of pedigree 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 parental forms.

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

4) Distant or interspecific hybridization - crossbreeding of two individuals of different species. It is used to combine the valuable qualities of individuals of different species. So 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, hares hare and hare = cuff.

Wild sheep argali and fine-fleeced merino sheep = archaromerinos

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

Problem - infertility interspecific hybrids. It occurs due to the fact that different species have a different number and structure of chromosomes, therefore, conjugation and the process of chromosome divergence during meiosis are disturbed.

It is especially difficult to overcome infertility in animal hybrids. In 1924 Karpechenko created a cabbage-rare hybrid and for the first time overcame infertility using the method polyplodization . He crossed radish and cabbage (2n-18; n-9 xp-m). But during meiosis, the chromosomes did not conjugate and did not disperse, 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 the restoration of fertility became possible.

In animals, it has become possible to obtain hybrids using cell engineering.

Selection

Artificial selection - creation of new breeds and varieties through the systematic conservation and reproduction of individuals with certain characteristics. At first, the selection was carried out unconsciously: a person carried out it from the beginning of the domestication of animals. Modern selection is carried out consciously, based on the 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.

- mass aimed at maintaining the group. It is used mainly for microorganisms and cross-pollinated plants. The selection is carried out according to phenotype , thereby the desired feature is increasingly developed.

- individual aimed at the preservation of individuals. It is used for self-pollinated plants (obtaining clean lines) and animals. Since the period for obtaining offspring in animals is quite long, selection is carried out according to genotype , for reproduction leave individual individuals.

Mutagenesis

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

Selection features

1) Plants

Characterized by sexual and asexual reproduction, mass selection by phenotype is used. different forms of hybridization. Polyploidy is used to increase the resistance of varieties and overcome the sterility of hybrids.

Michurin – mentor method : directional effect of the host plant on the properties of a young hybrid after grafting.

Features of animal breeding

Animals reproduce only sexually, which greatly limits breeding 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 the selection of microorganisms

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. Thus, a strain of the penicillium fungus was obtained, the productivity of which was increased several times.

Modern complementary breeding methods .

1. Artificial insemination.

2. Hormonal super-ovulation.

3. Embryo transfer.

Darwin's views

Darwin studied the methods of breeding new breeds and established the stages: the breeder selects individuals with the traits he needs; receives offspring from them; selects individuals in which the desired trait is expressed better. After several generations, the trait is fixed, becomes stable, 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. Transferability of traits by inheritance.

3. Artificial selection.

Fill out an application for preparation for the exam in biology or chemistry

Short form of feedback

Send your good work in the knowledge base is simple. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Hosted at http://www.allbest.ru/

Option 10.

QUESTION #1

Genetics is the theoretical basis of selection. Selection. The teachings of N.I. Vavilov about the centers of diversity and origin of cultivated plants. Basic breeding methods: hybridization, artificial selection

Breeding (from the Latin selectio, seligere - selection) is the science of methods for creating highly productive plant varieties, animal breeds and strains of microorganisms.

Initially, selection was based on artificial selection, when a person selects plants or animals with traits of interest to him. Until the XVI-XVII centuries. selection occurred unconsciously, that is, a person, for example, selected the best, largest wheat seeds for sowing, without thinking that he was changing the plants in the direction he needed.

Only in the last century, man, not yet knowing the laws of genetics, began to use selection consciously or purposefully, crossing those plants that satisfied him to the greatest extent.

However, by the method of selection, a person cannot obtain fundamentally new properties in bred organisms, since during selection it is possible to isolate only those genotypes that already exist in the population. Therefore, to obtain new breeds and varieties of animals and plants, hybridization (crossing) is used, crossing plants with desirable traits and, in the future, selecting from the offspring those individuals whose beneficial properties are most pronounced.

Modern breeding is a vast area human activity, which is a fusion of various branches of science, agricultural production and its complex processing. In the course of selection, stable hereditary transformations of various groups of organisms occur. By figurative expression N.I. Vavilov, "... selection is an evolution directed by the will of man." It is known that the achievements of selection were widely used by Charles Darwin in substantiating the main provisions of evolutionary theory. Modern selection is based on the achievements of genetics and is the basis of efficient highly productive agriculture and biotechnology.

Tasks of modern breeding

Creation of new and improvement of old varieties, breeds and strains with economically useful features.

Creation of technological highly productive biological systems that maximize the use of raw materials and energy resources of the planet.

Increasing the productivity of breeds, varieties and strains per unit area per unit of time.

Improving the consumer quality of products.

Reducing the share of by-products and their complex processing.

Reducing the share of losses from pests and diseases.

The greatest contribution to the study of the diversity of cultivated plants was made by the Russian breeder N.I. Vavilov.

“I don’t feel sorry for giving my life for the smallest thing in science…”

N.I. Vavilov was born on November 26, 1887 in Moscow. By the time he graduated from a commercial school, he already knew for sure that he would be a biologist. In 1906, Nikolai Ivanovich entered the Moscow Agricultural Institute. Already in his student years, his remarkable qualities began to appear.

In 1913 N.I. Vavilov was sent abroad for scientific work. In Merton (England), in the genetic laboratory of the Horticultural Institute. There he continued his research on the immunity of cereals.

For several months, Nikolai Ivanovich worked in the laboratory of genetics at the University of Cambridge; in France, he visited the largest seed company of Vilmorin, where he got acquainted with the latest achievements selection in seed production, in the susceptibility of various plant varieties. The results of these studies with the wide use of the experiment were summarized in the monograph "Plant immunity to infectious diseases"(1919). In 1917, N. I. Vavilov received an invitation to head the Department of Genetics, Breeding and Private Farming at the Saratov Higher Agricultural Courses and moved to Saratov. At the same time, he continued a wide field study of varieties of various agricultural plants, in primarily cereals.

He took an active part in the organization in 1923 of the first All-Union Agricultural Exhibition in Moscow. Vavilov's authority as a scientist and organizer of science grew. In 1924, the Department of Applied Botany and Breeding was transformed into the All-Union Institute of Applied Botany and New Crops under the Council of People's Commissars (since 1930 - the All-Union Institute of Plant Growing VIR), and N. I. Vavilov was approved as its director. By the end of the 1920s, the All-Union Institute of Applied Botany and New Cultures had become one of the world's largest and most famous research centers for the study of cultivated plants. Vavilov devoted all his energy to raising agriculture to new level. Dying of starvation in the Gulag, he thought about his homeland, about all of humanity. In an effort to prove the need for science - genetics, capable of creating new varieties of plants that will save humanity from hunger and satisfy the growing need for food. The bright and wonderful life of Nikolai Ivanovich will long attract the attention of researchers. Our youth should know this great life, which can be called the feat of a scientist, should learn from it how to work selflessly and how to love their homeland and science.

The teachings of N.I. Vavilov on the origin of cultivated plants

The doctrine of the source material is the basis of modern breeding. The source material serves as a source of hereditary variability - the basis for artificial selection. N.I. Vavilov established that there are areas on Earth with especially high level genetic diversity of cultivated plants, and identified the main centers of origin of cultivated plants.

Centers of origin of cultivated plants

For each center, the most important agricultural crops characteristic of it have been established.

1. Tropical center - includes the territories of tropical India, Indochina, South China and the islands of Southeast Asia. At least one quarter of the world's population still lives in tropical Asia. In the past, the relative population of this territory was even more significant. About one third of the currently cultivated plants originate from this center. It is the birthplace of plants such as rice, sugar cane, tea, lemon, orange, banana, eggplant, as well as a large number of tropical fruits and vegetables.

2. East Asian center - includes temperate and subtropical parts of Central and East China, Korea, Japan and most of about. Taiwan. Approximately one quarter of the world's population also lives in this territory. About 20% of the world's cultural flora originates from East Asia. This is the birthplace of such plants as soybeans, millet, persimmons, and many other vegetable and fruit crops.

3. Southwest Asian center - includes the territories of the inner upland Asia Minor (Anatolia), Iran, Afghanistan, Central Asia and Northwestern India. The Caucasus also adjoins here, the cultural flora of which, as studies have shown, is genetically related to Western Asia. Homeland of soft wheat, rye, oats, barley, peas, melons.

This center can be subdivided into the following foci:

a) Caucasian with many original types of wheat, rye and fruit. For wheat and rye, as shown by comparative studies, this is the most important world focus of their species origin;

b) Western Asia, including Asia Minor, Inner Syria and Palestine, Transjordan, Iran, Northern Afghanistan and Central Asia together with Chinese Turkestan;

c) Northwest Indian, including, in addition to Punjab and adjacent provinces North India and Kashmir also Balochistan and Southern Afghanistan.

4. Mediterranean center - includes countries located along the coast mediterranean sea. This remarkable geographical center, characterized in the past by the greatest ancient civilizations, has given rise to approximately 10% of the cultivated plant species. Among them are durum wheat, cabbage, beets, carrots, flax, grapes, olives, and many other vegetable and fodder crops.

5. Abyssinian center. Total number species of cultivated plants associated in their origin with Abyssinia does not exceed 4% of the world's cultural flora. Abyssinia is characterized by a number of endemic species and even genera of cultivated plants. Among them are such as coffee tree, watermelon, cereal. Within the New World, an amazingly strict localization of the two centers of speciation of the main cultivated plants has been established.

6. Central American center covering a vast territory North America including southern Mexico. Three centers can be distinguished in this center:

a) Mountain southern Mexican,

b) Central American,

c) West Indian island.

About 8% of various cultivated plants originate from the Central American center, such as corn, sunflower, American long-staple cotton, cocoa (chocolate tree), a number of beans, pumpkins, many fruits (guayava, anone and avocado).

7. Andean center, within South America, confined to the Andean ridge. This is the birthplace of potatoes and tomatoes. This is where the cinchona tree and the coca bush originate. As can be seen from the list of geographical centers, the initial introduction of the vast majority of cultivated plants into culture is associated not only with floristic regions that are distinguished by rich flora, but also with ancient civilizations. Only comparatively few plants were introduced in the past into cultivation from the wild flora outside the listed main geographical centers. The seven indicated geographical centers correspond to the most ancient agricultural cultures.

The South Asian tropical center is associated with a high ancient Indian and Indochinese culture. The latest excavations have shown the deep antiquity of this culture, synchronous with the Central Asian. The East Asian center is associated with ancient Chinese culture, and the Southwest Asian center is associated with ancient culture Iran, Asia Minor, Syria, Palestine and Assyro-Babylonia. The Mediterranean for many millennia BC concentrated the Etruscan, Hellenic and Egyptian cultures. The peculiar Abyssinian culture has deep roots, probably coinciding in time with the ancient Egyptian culture. Within the New World, the Central American Center is associated with the great Mayan culture, which reached great success in science and art before Columbus. Andean Center in South America combined in development with the remarkable pre-Inca and Inca civilizations.

Collection samples collected under the guidance of N.I. Vavilov, were kept in Leningrad at the All-Union Institute of Plant Industry (VIR), created by N.I. Vavilov in 1930. On the basis of the All-Union Institute of Applied Botany and New Cultures (formerly the Department of Applied Botany and Breeding, even earlier - the Bureau of Applied Botany).

During the years of the Great Patriotic War during the siege of Leningrad, VIR employees were on duty around the clock at the collection of seeds of grain crops. Many VIR employees died of starvation, but the invaluable species and varietal wealth, from which breeders around the world still draw material to create new varieties and hybrids, was preserved.

In the second half of the 20th century, new expeditions were organized to collect samples to replenish the VIR collection; at present, this collection includes up to 300,000 plant specimens belonging to 1,740 species.

Law of homologous series of hereditary variability

“Genetically close genera and species are characterized by similar series of hereditary variability with such regularity that, knowing the number of forms within one species, one can foresee the finding of parallel forms in other related species and genera.”

N.I. Vavilov found that "an important point in assessing the material for selection is the presence in it of a variety of hereditary forms."

Diversity of genes and genotypes in N.I. Vavilov called the genetic potential of the source material.

Systematizing the doctrine of the source material, N.I. Vavilov formulated the law of homological series (1920):

1. Species and genera that are genetically close are characterized by similar series of hereditary variability with such regularity that, knowing the number of forms within one species, one can foresee the occurrence of parallel forms in other species and genera.

2. Whole families of plants are generally characterized by certain cycle variability that passes through all the genera and species that make up the family.

According to this law, genetically close species and genera have similar genes that give a similar series of multiple alleles and trait variants. For example, within different genera of cereals, there is a parallel variability in grain color:

Theoretical and practical significance of the law of homologous series:

N.I. Vavilov clearly distinguished between intraspecific and interspecific variability. At the same time, the species was considered as an integral, historically established system.

N.I. Vavilov showed that intraspecific variability is not unlimited and is subject to certain patterns.

The law of homologous series is a guide for breeders to predict the possible variations of traits.

N. I. Vavilov was the first to carry out a targeted search for rare or mutant alleles in natural populations and populations of cultivated plants. Nowadays, the search for mutant alleles to increase the productivity of strains, varieties and breeds continues.

This law may help rational use organic wealth of the earth. The law of homologous series is recognized as one of the fundamental laws of wildlife. It facilitates the search for the economic traits of plants and animals necessary for breeding.

Selection Methods

Modern breeding uses a whole range of methods based on the latest achievements of many sciences: genetics, cytology, botany, zoology, microbiology, agroecology, biotechnology, information technologies etc. However, hybridization and artificial selection remain the main specific methods of selection.

Hybridization

Crossing organisms with different genotypes is the main method for obtaining new combinations of traits. Sometimes hybridization is necessary, for example, to prevent inbreeding depression. Inbreeding depression is manifested during closely related crossing and is expressed in a decrease in productivity and vitality. Inbreeding depression is the opposite of heterosis.

There are the following types of crosses:

Intraspecific crosses - different forms are crossed within a species. Intraspecific crossings also include crossings of organisms of the same species living in different ecological conditions and / or in different geographical areas (ecological-geographical crossings). Intraspecific crosses underlie most other crosses.

Closely related crosses - inbreeding in plants and inbreeding in animals. They are used to obtain clean lines.

Interline crosses - representatives of pure lines are crossed (and in some cases - different varieties and breeds). Interline crossings are used to suppress inbreeding depression, as well as to obtain the effect of heterosis.

Crossings (back-crosses) are crossings of hybrids (heterozygotes) with parental forms (homozygotes). For example, crosses of heterozygotes with dominant homozygous forms are used to prevent the phenotypic expression of recessive alleles.

Analyzing crosses (they are a kind of back-crosses) are crosses of dominant forms with an unknown genotype and recessive-homozygous tester lines. Such crosses are used to analyze sires by offspring.

Saturating (replacement) crosses are also a type of backcrosses. With multiple backcrosses, selective (differential) substitution of alleles (chromosomes) is possible.

Distant crosses - interspecific and intergeneric. Usually, distant hybrids are sterile and are propagated vegetatively; to overcome the infertility of hybrids, doubling the number of chromosomes is used, in this way amphidiploid organisms are obtained: rye-wheat hybrids (triticale), wheat-couch grass hybrids.

Somatic hybridization is hybridization based on the fusion of somatic cells of completely dissimilar organisms.

Artificial selection has been and remains the most important selection method. However, the selection process includes two groups of activities: evaluation of the source material and selective reproduction (reproduction) of the selected organisms or their parts.

Selection is the process of differential (unequal) reproduction of genotypes. At the same time, one should not forget that, in fact, selection is carried out according to phenotypes at all stages of the ontogeny of organisms (individuals). The ambiguous relationship between genotype and phenotype involves testing selected plants for progeny.

There are many forms of artificial selection. Let us consider in more detail the most commonly used forms of selection.

Mass selection - the entire group is subjected to selection. For example, seeds from the best plants are combined and sown together. Mass selection is considered a primitive form of selection, since it does not allow eliminating the influence of modification variability. Used in seed production. It is recommended for the selection of new plants introduced into the culture or crops that are not well developed in terms of breeding.

Let us consider the methods for evaluating the source material using plants as an example.

In the process of selection, the material is evaluated according to its economic and biological properties, which are the object of selection. But regardless of the characteristics of the object and the tasks of selection, the material is evaluated according to the following criteria:

A certain rhythm of development corresponding to the soil and climatic conditions in which the further exploitation of the variety is planned;

High potential productivity with high product quality;

Resistance to the adverse effects of physical and chemical environmental factors (frost resistance, heat resistance, drought resistance, resistance to various types of chemical pollution);

resistance to diseases and pests;

Responsiveness to agricultural technology.

Ideally, the variety should not meet individual requirements, but their complex. However, in practice this often turns out to be impossible, and that is why the creation of compositions consisting of lines (clones) with different hereditary properties is considered the fastest and most reliable way to increase the overall sustainability of agro ecosystems.

selection hybridization artificial selection

QUESTION #2

Species and spatial structure of ecosystems. Food connections, cycling of substances and energy conversion in ecosystems

c) Muller

b) Schmalhausen

d) Kovalevsky

The structure of the ecosystem is multifaceted. Distinguish between species and spatial structure.

The species structure of an ecosystem is the diversity of species, the relationship and ratio of their numbers. Different communities that make up an ecosystem consist of a different number of species - species diversity. In the taiga forest, on an area of 100 m, as a rule, plants grow about 30 various kinds, and in the meadow along the river - twice as much.

Species diversity depends on the ratio of the number of species in the ecosystem. For example, 1000 birds live in a suburban forest: 100 individuals of 10 different species each. In another suburban forest there are also 1000 birds of the same 10 species, but 920 of the birds are crows and jackdaws (two species), and individuals of the remaining 8 species are much less common, on average 10 individuals.

The decrease in species diversity threatens the very existence of the species due to the reduction of genetic diversity - the stock of recessive alleles that ensures the adaptability of populations to changing environmental conditions.

In turn, species diversity serves as the basis for ecological diversity - the diversity of ecosystems. The totality of genetic, species and ecological diversity makes up the biological diversity of the planet.

Spatial structure of the ecosystem.

Populations of different species in an ecosystem are distributed in a certain way - they form a spatial structure. There are vertical and horizontal structures of the ecosystem.

Vegetation forms the basis of the vertical structure.

The plant community determines, as a rule, the appearance of the ecosystem. Plants largely influence the conditions for the existence of other species. In the forest, these are large trees, in the meadows and in the steppes - perennial grasses, and in the tundra, mosses and shrubs dominate.

Living together, plants of the same height create a kind of floors - tiers. In a forest, for example, tall trees make up the first (upper) tier, the second tier is formed from young trees of the upper tier and from adult trees that are smaller in height. The third tier consists of shrubs, the fourth - of tall grasses. The lowest tier, where very little light enters, is made up of mosses and undersized grasses.

Layering is also observed in herbaceous communities (meadows, steppes, savannahs). There is also an underground layering, which is associated with different depths of penetration into the soil of the root systems of plants: in some, the roots go deep into the soil, reach the groundwater level, while others have a surface root system, trapping water and nutrients from the upper soil layer.

Animals are also adapted to life in one or another plant layer (some do not leave their layer at all).

Any community can be represented as a food web in which numerous food chains are intricately intertwined. Food chains transfer substances and energy in the ecosystem from link to link. Each link in the food chain is called a trophic (from the Greek trofo - food) level.

The first trophic level is made up of producers, autotrophic organisms - plants and some bacteria. Basically, plants create organic matter from inorganic by using the energy of sunlight (photosynthesis), and bacteria - by using energy chemical reactions oxidation of mineral substances (chemosynthesis).

The second trophic level is made up of herbivorous animals - consumers. The third level is carnivores (predators), the fourth level is animals that eat other carnivores, etc. Many animals cannot be attributed to one level, since they are omnivores, they can receive energy from several different trophic levels.

A variety of substances and energy move from one trophic level to another along the food chains as some organisms are eaten by others, undergoing numerous transformations. At the final stage, decomposers completely destroy organic substances, turning them into minerals.

This means that the existence of all ecosystems depends on a constant influx of energy from outside. How is it carried out energy metabolism in ecosystems?

All organisms need energy, and the only source of almost all energy on Earth is the sun. However, only 1% of the sun's light energy is captured by plants during photosynthesis and stored as chemical energy, while 99% is lost as heat and spent on evaporation. The energy stored by plants is transferred from one trophic level to another along the food chain. Part of the energy is lost during the transformation of food substances into molecules of the predator's body, and part passes through the intestinal tract of the predator unchanged.

Haeckel-Muller biogenetic law (also known as "Haeckel's law", "Muller-Haeckel's law", "Darwin-Muller-Haeckel's law", "basic biogenetic law"): every living being in its individual development (ontogenesis) repeats in a certain degree of form passed by its ancestors or its species (phylogenesis).

played important role in the history of the development of science, but was later refuted and in its original form is not recognized by modern biological science.

Biogenetic Law, one of the generalizations of evolutionary biology, linking individual development, or ontogeny, with historical development, or phylogeny. The biogenetic law established by the German scientists F. Müller (1864) and E. Haeckel (1866) states that the ontogenesis of any organism is a brief repetition (recapitulation) of the main stages of the phylogenesis of the species to which the given organism belongs.

The biogenetic law finds many confirmations in the data of comparative anatomy, embryology and paleontology. For example, in the embryos of birds and mammals, at a certain stage of embryonic development, the rudiments of the gill apparatus appear. This is because terrestrial vertebrates evolved from gill-breathing fish-like ancestors. Based on the biogenetic law and using embryological data, it is possible to recreate the course historical development certain groups of organisms. This is especially important in those cases when for k.-l. group, fossil remains of ancestral forms are unknown, i.e., with the incompleteness of the paleontological record.

The Haeckel-Muller biogenetic law: each individual in its individual development (ontogenesis) briefly and concisely repeats the history of the development of its species (phylogenesis).

a) Examples in animals:

* The vessels of the embryos of land vertebrates are similar to the vessels of fish;

* The human fetus has gill slits.

* Butterfly caterpillars and beetle larvae are similar to annelids.

* Tadpoles of amphibians are similar to fish.

b) Examples in plants:

* Kidney scales in the bud of plants develop like leaves.

* The petals of the buds are green at first, acquire their characteristic color.

* From the moss spores, a green thread first appears, similar to filamentous algae (pre-sprout).

c) Amendments to the biogenetic law.

* In embryos, the repetition of phylogenesis may be disturbed in connection with adaptations to living conditions in ontogeny. Appear: embryonic membranes, yolk sac in fish eggs, external gills in a tadpole, cocoon in a silkworm.

* Ontogeny does not fully reflect phylogeny due to the appearance of mutations that change the course of development of the embryo (in the embryo of a snake, all the vertebrae are laid at once, i.e. their number does not increase gradually; in birds, the five-fingered stage of limb development fell out, 4 fingers are laid in the embryo, and not 5, only 3 fingers grow in the wing).

* In ontogenesis, the embryonic stages of development are repeated, and not adult forms (the Lancelet repeats in ontogeny the general stages with a free-swimming ascidian larva, and not with its adult, fixed form).

G) Modern views about the biogenetic law.

* Severtsov showed that due to changes in development, some stages of development of the embryo can fall out; there are changes in the organs of the embryo that were not in the ancestors; new species emerge; new signs are revealed (for example, tailed (newts) and tailless (frogs) amphibians descended from one ancestor: the newt larva is long, because it has many vertebrae, the number of vertebrae in the frog larva has decreased due to mutation; the lizard embryo has fewer vertebrae, than in the snake embryo, due to developmental mutations).

QUESTION #3

The human races are:

a) three biological species

b) different populations of the same species

c) different populations of different species

View Homo sapiens is divided into three large races: Eurasian (Caucasoid), Asian-American (Mongoloid) and Australo-Negroid (Equatorial). Representatives of the Caucasian race are characterized by relatively fair skin, soft straight or wavy hair, thin lips, and a narrow protruding nose. Men usually grow beards and mustaches well. Within the race, there is great variability in hair and eye color, so it is divided into three large parts: light-colored northern (Scandinavians), dark-colored southern (Indians, Arabs) and Central European with an intermediate type of pigmentation.

Typical representatives of the Mongoloid race have dark skin of a yellowish tint, dark brown eyes, dark and straight coarse hair. In men, the hairline on the body is poorly developed. Most Mongoloids are characterized by epicanthus - a special fold of the upper eyelid that covers the inner corner of the eye. The nose is rather narrow. Representatives of the equatorial race are characterized by black curly hair, very dark skin and brown eyes. Beards and mustaches in men grow weakly. The nose is rather flat, slightly protruding, with wide wings. Most representatives have thick lips and a protruding jaw region of the skull.

Major human races

In modern humanity, there are three main races: Caucasoid, Mongoloid and Negroid. These are large groups of people that differ in some physical features, such as facial features, skin color, eyes and hair, hair shape. Each race is characterized by the unity of origin and formation in a certain territory.

Belongs to the European race indigenous people Europe, South Asia and North Africa. Caucasoids are characterized by a narrow face, a strongly protruding nose, and soft hair. The skin color of northern Caucasians is light, while that of southern Caucasians is predominantly swarthy.

The Mongoloid race includes the indigenous population of Central and East Asia, Indonesia, and Siberia. Mongoloids are distinguished by a large, flat, wide face, slit eyes, hard, straight hair, and dark skin color.

In the Negroid race, two branches are distinguished - African and Australian. The Negroid race is characterized by dark skin color, curly hair, dark eyes, a wide and flat nose.

Racial features are hereditary, but at present they are not essential for human life. Apparently, in the distant past, racial traits were useful for their owners: the dark skin of blacks and curly hair, creating an air layer around the head, protected the body from the effects of sun rays, the shape of the facial skeleton of Mongoloids with a larger nasal cavity, may be useful in warming cold air before it enters the lungs. According to mental abilities, i.e., the ability to know, creative and in general labor activity All races are the same. Differences in the level of culture are not associated with biological features people of different races, but with the social conditions of the development of society. Initially, some scientists confused the level of social development with biological characteristics and tried to find transitional forms among modern peoples that connect humans with animals. These mistakes were used by the racists, who began to talk about the alleged inferiority of some races and peoples and the superiority of others to justify the merciless exploitation and direct destruction of many peoples as a result of colonization, the seizure of foreign lands and the outbreak of wars.

The failure of racism is proved by the real science of races - racial science. Racial studies studies racial characteristics, origin, formation and history human races. The data obtained by racial science indicate that the differences between races are not sufficient to consider races as different. species of people. Mixing of races - miscegenation - occurred constantly, as a result of which intermediate types arose at the boundaries of the ranges of representatives of different races, smoothing out the differences between races.

QUESTION #4

Butterfly caterpillars are similar to annelids - this is evidence of evolution from the field of science:

a) biogeography b) embryology

c) comparative anatomy d) paleontologists

Paleontological evidence for evolution

Paleontology is the science of the organic world of past geological epochs, that is, of organisms that once lived on Earth and are now extinct. In paleontology, paleozoology and paleobotany are distinguished.

Paleozoology studies the remains of fossil animals, while paleobotany studies the remains of fossil plants. Paleontology directly proves that the organic world of the Earth in different geological epochs was different, it changed and developed from primitive forms of organisms to more highly organized forms. Paleontological studies make it possible to establish the history of the development of various forms of organisms on Earth, to identify related (genetic) relationships between individual organisms, which contributes to the creation of a natural system organic world Earth. To substantiate the theory of evolution, Charles Darwin widely used numerous evidence from the field of paleontology, biogeography, and morphology. Subsequently, facts were obtained that recreate the history of the development of the organic world and serve as new evidence of the unity of the origin of living organisms and the variability of species in nature.

Paleontological finds are perhaps the most convincing evidence of the evolutionary process. These include fossils, imprints, fossils, fossil transitional forms, phylogenetic series, sequence of fossil forms. Let's consider some of them in more detail.

Fossil transitional forms - forms of organisms that combine the features of older and younger groups. Among plants, psilophytes are of particular interest. They originated from algae, were the first of the plants to make the transition to land and gave rise to higher spore and seed plants. Seed ferns are a transitional form between ferns and gymnosperms, and cycads are between gymnosperms and angiosperms.

Among the fossil vertebrates, forms can be distinguished that are transitional between all classes of this subtype. For example, the oldest group of lobe-finned fish gave rise to the first amphibians - stegocephals. This was possible due to the characteristic structure of the skeleton of the paired fins of the lobe-finned fish, which had the anatomical prerequisites for their transformation into the five-fingered limbs of the primary amphibians. Forms are known that form the transition between reptiles and mammals. These include animal lizards (foreigners). And the link between reptiles and birds was the first bird (Archeopteryx).

Paleontological series - series of fossil forms, connected with each other in the process of evolution and reflecting the course of phylogenesis (from the Greek phylon - genus, tribe, genesis - origin). A classic example the use of series of fossil forms to elucidate the history of a particular group of animals is the evolution of the horse. Russian scientist V.O. Kovalevsky (1842-1883) showed the gradual evolution of the horse, establishing that successive fossil forms became more and more similar to modern ones.

Modern one-toed animals descended from small five-toed ancestors that lived in forests 60-70 million years ago. Climate change has led to an increase in the area of the steppes and the settlement of horses on them. Movement over long distances in search of food and in defense against predators contributed to the transformation of the limbs. In parallel, the size of the body, jaws increased, the structure of the teeth became more complicated, etc.

To date, a sufficient number of paleontological series (proboscis, carnivores, cetaceans, rhinos, some groups of invertebrates) are known, which prove the existence of an evolutionary process and the possibility of the origin of one species from another.

In conclusion, we can conclude that the briefly considered phenomena prove that the organic world of the Earth is in a state of constant slow gradual development, i.e. evolution, while development has gone and goes from simple to complex.

QUESTION #5

A scientist who had a metaphysical view of evolution:

a) C. Linnaeus b) Lamarck

c) C. Darwin d) A. Wallace

The evolutionary idea - as the idea of the historical development of wildlife and the variability of species, originated a very long time ago. In the II-I millennia BC. in China and India, there were teachings about the possibility of transforming some living beings into others, about the origin of man from monkeys. Thoughts about the natural development of all living beings from primary matter are found among philosophers Ancient Greece Heraclitus and Aristotle.

However, between the evolutionary ideas of ancient thinkers and modern scientists, the similarity is purely external. The views of the ancient thinkers had the character of conjectures, without strict scientific substantiation by facts. Ancient civilizations in Europe were replaced by the Middle Ages. The prevailing idea was the immutability of all life on Earth.

Evolutionary ideas took shape in the form of a doctrine only with the emergence of a materialistic worldview in philosophy. The idealistic worldview that prevailed until then proclaimed that God was the creator of all nature. And according to the materialistic doctrine, the inanimate initially arose, and then Live nature and in the course of its long development highly evolved beings emerged. No one created them, they are the result of evolutionary transformations of matter, the peak of which was man.

With the accumulation of scientific information, views in philosophy change - a materialistic doctrine is formed; in biology, the first ideas about evolution appear, which were already contained in the later works of K. Linnaeus, and then the evolutionary doctrine of J.-B. Lamarck (XVIII-XIX centuries).

in Russia in the 18th century. evolutionary ideas were formed, which were reflected in the works of M. V. Lomonosov and A. N. Radishchev. In the 19th century, K. M. Baer made a great contribution to science with studies of the embryonic development of animals; the laws developed by him were noted by Ch. Darwin and called "the law of germinal similarity." The zoologist K. F. Roulier substantiated the position on the relationship between the organism and the external environment. After analyzing the importance of heredity and variability as conditions for the adaptation of species to the environment, he came to the conclusion that this is a gradual, evolutionary process. In the classic work of A. I. Herzen "Letters on the Study of Nature" it is argued that matter is not created or destroyed by anyone, and all its forms and properties are the product of its development.

Contribution to science by C. Linnaeus (1707-1778)

He discovered about 1.5 thousand plant species; - described about 10 thousand plant species and about 4.5 thousand animal species;

Developed short and clear definitions of each group of organisms, which greatly facilitated their description; - Defined the concept of "kind".

He introduced Latin into science and a convenient binary (double) nomenclature instead of the cumbersome polynomial names used earlier; this nomenclature is used in our time ("The System of Nature", 1735);

Developed the principles for constructing a classification of wildlife ("Philosophy of Botany"). On these principles, he built a new scientific system of living nature, which included all animals and all plants known at that time and was the most perfect for that time;

in streamlining rapidly accumulating knowledge led to the need to systematize them. Practical dependences are created on their benefit to a person or the harm they bring.

K. Linnaeus created the most perfect system of the organic world for that time, including in it all the then known animals and plants. In many cases, he correctly combined the types of organisms according to the similarity of the structure. The system of K. Linnaeus was artificial, since it did not reflect the relationship and similarity of plants and animals in terms of the totality of essential structural features, did not indicate the unity of the origin of living organisms. K. Linnaeus was aware of the artificiality of his system and pointed out the need to develop a natural system of nature. He wrote: " artificial system serves only until a natural one is found.

According to his worldview, K. Linnaeus was a metaphysician and a creationist. According to metaphysical ideas, nature is something frozen, not changing in time. During the reign of religious ideas, scientists believed that the types of organisms were created independently of each other by the Creator and are unchanged. “There are so many species,” noted K. Linnaeus, “how many various forms created at the beginning of the world by the Almighty. That is why the search for nature meant for biologists to try to penetrate into the plan of creation that guided God, creating all life on earth.

LIST OF USED LITERATURE

1. Sivoglazov N.I., Agafonova I.B., Zakharova E.T. General biology. A basic level of. 10 - 11 class. - M.: Bustard, 2005.

2. Belyaev D.K. General biology: tutorial for grades 10-11 of educational institutions / P.M. Borodin, N.N. Vorontsov and others - Moscow: Education, 2002.

3. Sivkova V.V. New directory student grade 5-11. Universal allowance. Publishing house "Ves", St. Petersburg - 2002.

4. Anastasova L.P. and others. "Man and the Environment" (M., "Enlightenment", 1981) Grade 9

5. Morozov E.I., Tarasevich E.I., Anokhina V.S. Genetics in questions and answers. Minsk. "University". 1989.

6. Fogel F., Motulski A. Human genetics. Moscow. "World". 1990.

7. Demyanenkov E.N. Biology in questions and answers. - Moscow, 1996.

8. Korotkova L.S. Didactic material on general biology grade 10. Moscow "Enlightenment" 1984

9. Nikeshov A.I. Schoolchildren's guide to biology grades 6-9.

Moscow "Drofa" 1996

10. Dmitrieva T.A. Didactic materials: Biology. Man. General biology. M Bustard 2002

REVIEW

_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Hosted on Allbest.ru

...

What is genetics?

The science of genes 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.
The study of the implementation of such information in the process of individual development of the organism, taking into account the influence of the environment.
The study of the causes and mechanisms of the variability of 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 breeding:

Determining the efficiency of selection and choosing 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 by artificial means.
Development of measures aimed at protecting the environment, for example, from the influence of mutagens, pests.
The fight against hereditary pathologies.
Making 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 a 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 - a set of genes, the hereditary basis of an organism.
Phenotype - a set of qualities that an organism acquires in the process of individual development.

Stages of development of genetics

The development of genetics and selection took place in several stages. Consider the periods of formation of the science of genes:

Genetic Science Methods

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, which differ in one (maximum several) characteristics. The goal is to obtain hybrid generations, which makes it possible to analyze the nature of the inheritance of traits and count on obtaining offspring with the necessary qualities.
genealogy method. Based on analysis 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. Based on a comparison of monozygotic individuals, it 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 the analysis of the nucleus and intracellular components, comparing the results obtained with the norm for 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 plasma protein polymorphism, such as milk or blood, which provides information on 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 makes it possible 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 the analysis of 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 a selection?

Breeding is a science that studies methods for creating new varieties and hybrids of plants, as well as animal breeds. breeding is genetics.

The purpose of science is to improve the qualities of an organism or obtain in it the properties necessary for a person by influencing heredity. Selection cannot create new species of organisms. Selection can be considered one of the forms of evolution in which artificial selection is present. Thanks to her, humanity is provided with food.

The main tasks of science:

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

A feature is the complexity of science. It is closely related to anatomy, physiology, morphology, taxonomy, ecology, immunology, biochemistry, phytopathology, crop production, animal husbandry and many other sciences. Knowledge about fertilization, pollination, histology, embryology and molecular biology are significant.

Achievements of modern selection make it possible to control the heredity and variability of living organisms. The significance of genetics for breeding and medicine is reflected in the purposeful control of the succession of qualities and the possibilities of obtaining hybrids of plants and animals to meet human needs.

Stages of selection development

Since ancient times, man has been breeding and selecting plants and animals for agricultural purposes. But such work was based on observation and intuition. The development of breeding and genetics took place almost simultaneously. Consider the stages of formation of selection:

During the development of crop and livestock breeding, selection began to be of a mass nature, and the formation 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 yields. English breeders P. Shiref and F. Gallet studied wheat varieties. In Russia, the Poltava Experimental Field was created, where studies of the varietal composition of wheat were carried out.
Breeding 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 the centers of origin of plants for cultural purposes, ecological and geographical principles of selection, knowledge about the source material of plants and their immunity was obtained. The All-Union Institute of Applied Botany and New Cultures was founded under the direction of N. I. Vavilov.
Research from the end of the 20th century to the present day is complex, selection closely interacts with other sciences, especially with genetics. Hybrids with high agroecological adaptation have been created. Modern research focuses on obtaining high productivity in hybrids and resistance to biotic and abiotic stressors.

Selection Methods

Genetics considers 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 get new genotypes. In the method, intraspecific (crossing occurs within the same species) and interspecific hybridization (crossing of different species) are distinguished. Carrying out inbreeding allows you to fix hereditary properties while reducing the viability of the organism. If outbreeding is carried out in the second or subsequent generations, then the breeder receives high-yielding and resistant hybrids. It has been established that with distant crossing, the offspring is sterile. Here the significance of genetics for breeding is expressed in the possibility of studying genes and influencing the fertility of organisms.
Polyploidy is the process of increasing chromosome sets, which allows fertility to be achieved in infertile hybrids. It is noticed 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 its treatment with a mutagen. After the end of the mutation, the breeder receives information about the influence of the factor on the organism and the acquisition of new qualities by it.
Cell engineering is designed to construct a new type of cell through cultivation, reconstruction and hybridization.
Genetic engineering makes it possible to isolate and study genes, to manipulate them in order to improve the qualities of organisms and breed new species.

Plants

In the process of studying the growth, development and excretion useful properties Plant genetics and plant breeding are closely related. Genetics in the field of analysis of the vital activity of plants 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:

The development of one specific organism.
The control signaling systems plants.
Expression of genes.
Mechanisms of interaction between plant cells and tissues.

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

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

Thanks to genetics, the method of crossing and individual selection is used in breeding. The development of the science of genes makes it possible to apply in breeding such methods as polyploidy, heterosis, experimental mutagenesis, chromosomal and genetic engineering.

Animal world

Animal breeding and genetics are branches of science that study the features of the development of representatives of the animal world. Thanks to genetics, a person gains knowledge about heredity, genetic characteristics and variability of the body. And selection allows you to select for use only those animals whose qualities are necessary for man.

Since ancient times, people have been selecting animals that, for example, are more suitable for use in agriculture or hunting. Great importance for breeding have economic features and exterior. Thus, farm animals are evaluated according to appearance and the quality of their offspring.

The use of knowledge of genetics in breeding allows you to control the offspring of animals and their necessary qualities:

virus resistance;
increase in milk yield;
individual size and physique;
climate tolerance;
fertility;
sex of offspring;
elimination of hereditary disorders in descendants.

Animal breeding has become widespread not only in order to meet the primary human needs for nutrition. Today you can observe many domestic animal breeds, artificially bred, 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 often face the problem of non-breeding of species among the first generation of hybrids and a significant decrease in the fecundity of offspring. Modern scientists actively solve such questions. Main task scientific works is the study of the patterns of compatibility of gametes, the fetus and the mother's body at the genetic level.

Microorganisms

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

The study of genetics and the selection of microorganisms are carried out in a shorter time than with crop production and animal husbandry. This is due to the rapid reproduction and change of generations of microorganisms. Modern methods of breeding 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;
ethyleneimine;
nitrosomethylurea;
the use of nitrates;
acridine paints.

For the effectiveness of the mutation, frequent treatments of the microorganism with small doses of the 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, the immunity that manifests itself in them. Such knowledge is important for the fight against pathogens.

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

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

For this, the following methods are used:

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

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

Achievements 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 of genetics provides new opportunities for the development of such technologies: energy and resource-saving, waste-free, knowledge-intensive, safe. In biotechnology, the following methods are used: cell and chromosome 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 areas of human life.

The message of genetics is the theoretical basis of breeding briefly. Genetics as the theoretical basis of Selection. What is the theoretical basis of selection

Heredity

Variability

Genotype

Phenotype

Selection

What have we learned?

Fill out an application for preparation for the exam in biology or chemistry

Send your good work in the knowledge base is simple. Use the form below

Similar Documents

What is genetics?

Stages of development of genetics

Genetic Science Methods

What is a selection?

Stages of selection development

Selection Methods

Plants

Animal world

Microorganisms

Medicine and biotechnology