Humanity has long been engaged in the selection of plants and animals suitable to meet the needs of the population. This knowledge is combined into science - 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 the description of these two sciences and the features of their application.
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.
- Studying the causes andmechanisms of 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:
- 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 by artificial means.
- Development of measures aimed at protecting the environment, for example, from the influence of mutagens, pests.
- Fight against hereditary pathologies.
- Making progress on 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 preserving and transmitting genetic information to descendants, inherent in all living organisms, which cannot be taken away.
- 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 individualdevelopment.
Stages of development of genetics
The development of genetics and selection has gone through several stages. Consider the periods of formation of the science of genes:
- Until the 20th century, research in the field of genetics was abstract, they had no practical basis, but were based on observations. The only advanced work of that time was the study of G. Mendel, published in the Proceedings of the Society of Naturalists. But the achievement did not become widespread and was unclaimed until 1900, when three scientists discovered the similarity of their experiments with Mendel's research. It was this year that began to be considered the time of the birth of genetics.
- Approximately in 1900-1912, the laws of heredity were studied, revealed during hybridological experiments that were carried out on plants and animals. In 1906, the English scientist W. Watson proposed the introduction of the concepts of "gene" and "genetics". And after 3 years, V. Johannsen, a Danish scientist, proposed introducing the concepts of "phenotype" and "genotype".
- Approximately in 1912-1925, the American scientist T. Morgan and his students developed the chromosome theory of heredity.
- Around 1925-1940, mutation patterns were first obtained. Russian researchers G. A. Nadson and G. S. Filippov discovered the effect of gamma radiation on the appearance of mutating genes. S. S. Chetverikov contributed to the development of science by highlighting genetic and mathematical methods for studying the variability of organisms.
- From the middle of the 20th century to the present day, research has been carried out on genetic changes at the molecular level. At the endIn the 20th century, a DNA model was created, the essence of the gene was determined and the genetic code was deciphered. In 1969, a simple gene was synthesized for the first time, and later it was introduced into a cell and the change in its heredity was studied.
Methods of Genetic Science
Genetics, as the theoretical basis of breeding, 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 allows us to analyze the nature of the inheritance of traits and expect to obtain offspring with the necessary qualities.
- Genealogy method. Based on the analysis of the family tree, which allows you to trace the transfer of genetic information through generations, adaptability to diseases, and also to characterize the value of an individual.
- Twin method. Based on comparison of monozygotic individuals, 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 with the norm for the following parameters: the number of chromosomes, the number of their arms and structural features.
- The method of biochemistry is based on the study of the functions and structure of certain molecules. For example, the use of various enzymes is used inbiotechnology and genetic engineering.
- The biophysical method is based on the study of polymorphism of plasma proteins, 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 application of mathematical analysis in biology, which allows analyzing 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 selection?
Breeding is a science that studies methods of creating new varieties and hybrids of plants, as well as breeds of animals. The theoretical basis of 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 yield;
- increasing the resistance of organisms to diseases, pests, changes in climatic conditions.
The peculiarity 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 of fertilization, pollination, histology, embryology and molecular biology are significant.
Achievements of modern breeding allow you to control the heredity and variability of living organisms. The importance 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 selection development:
- During the development of crop and livestock breeding, selection began to be massive, 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, wherestudies of the varietal composition of wheat.
- Breeding as a science began to develop since 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 about the source material of plants and their immunity. The All-Union Institute of Applied Botany and New Cultures was created under the leadership 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. Current research is focusing on getting hybrids to be highly productive and to withstand 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 (mass selection) can also be selected. The definition 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 one 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 to achieve fertility in infertile hybrids. It has been observed that some cultivated plants after polyploidy have higher fertility 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.
- Gene engineering allows you to isolate and study genes, manipulate them in order to improve the qualities of organisms and breed new species.
Plants
In the process of studying the growth, development and selection of useful properties of plants, genetics and selection are closely interrelated. Genetics in the field of plant life analysis deals withissues of studying the features 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.
- Control of plant signaling systems.
- Gene expression.
- 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 being studied and successfully used not only by farmers and gardeners, but also by breeders in research organizations.
The use of genetics in breeding and seed production makes it possible to instill new qualities in plants that can be useful in various areas of human life, such as medicine or cooking. Also, knowledge of genetic characteristics makes it possible to obtain new varieties of crops that can grow in other climatic conditions.
Thanks to genetics, breeding uses the method of crossing and individual selection. The development of the science of genes makes it possible to apply such methods as polyploidy, heterosis, experimental mutagenesis, chromosomal and genetic engineering in breeding.
Animal World
Selection and genetics of animals 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 variabilityorganism. And selection allows you 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 breeding. Thus, farm animals are judged by the appearance and quality of their offspring.
The application 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;
- offspring gender;
- 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. 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 of breeding andgenetics 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 an 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 oversynthesis 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 these mutagens:
- ultraviolet;
- ionizing radiation;
- ethyleneimine;
- nitrosomethylurea;
- application of nitrates;
- acridine paints.
For mutation efficiencyfrequent treatments of the microorganism with small doses of the mutagen are used.
Medicine and Biotechnology
Common in the meaning of genetics for breeding and medicine is that in both cases, science allows you to study the heredity of organisms, manifested in their immunity. Such knowledge is important in the fight against pathogens.
The study of genetics in the field of medicine allows you to:
- prevent the birth of children with genetic abnormalities;
- prevent and treat 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 - matching twin pair;
- cytogenetic - study of chromosomes;
- biochemical - allows you to identify mutant alleys in DNA;
- dermatoglyphic - skin pattern analysis;
- modeling and others.
Modern research has identified approximately 2,000 inherited diseases. Mostly mental disorders. The study of genetics and the 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 of genetics provides new opportunities for the development of such technologies: energy and resource-saving, waste-free, knowledge-intensive, safe. In biotechnologythe 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.
