Since ancient times, mankind has been selecting suitable crops and animals to meet the needs of the population. This knowledge is combined into science - selection. Genetics, in turn, provides the basis for a more thorough selection and breeding of new varieties and breeds that are characterized by special qualities. In the article, we consider a 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:
- The 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 body, taking into account the influence of the environment.
- The study of the causes and mechanisms of variability of living organisms.
- Determining the relationship of selection, variability and heredity as factors in the development of the organic world.
Science is also involved in solving practical problems, in which the importance of genetics for selection is manifested:
- Determination of selection efficiency and selection of the most acceptable types of hybridization.
- Monitoring the development of hereditary factors in order to improve the object to obtain more significant qualities.
- Obtaining hereditarily modified forms artificially.
- Development of measures aimed at protecting the environment, for example, from the influence of mutagens and pests.
- 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 the property of preservation and transmission of genetic information 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 specific 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 the body.
- Phenotype - a set of qualities that the body acquires in the process of individual development.
Stages of Genetics
The development of genetics and selection went 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 did not have a 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 was not widespread and was unclaimed until 1900, until three scientists discovered the similarities of their experiments with the study of Mendel. This year was considered the time of the origin of genetics.
- Around 1900-1912, the laws of heredity were studied, revealed during hybridological experiments that were conducted 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”.
- Around 1912-1925, the American scientist T. Morgan and his students developed the chromosome theory of heredity.
- Around 1925-1940, mutation samples 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, highlighting the genetic and mathematical methods for studying the variability of organisms.
- From the middle of the 20th century to the present, studies of genetic changes at the molecular level have been carried out. At the end of the 20th century, a DNA model was created, the essence of the gene was determined, and the genetic code was deciphered. In 1969, the synthesis of a simple gene first occurred, and later it was introduced into the cell and the change in its heredity was studied.
Genetic Science Methods
Genetics, as the theoretical basis of selection, uses certain methods in its research.
These include:
- Hybridization method. It is based on the crossing of species with a clean 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 characters and count on obtaining offspring with the necessary qualities.
- Genealogy method. It is based on the analysis of the genealogical tree, which allows us to trace the transmission of genetic information through generations, adaptability to diseases, and also to characterize the value of the individual.
- Twin method. Based on a comparison of monozygous individuals, it is used if 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 in such parameters: the number of chromosomes, the number of their shoulders and structural features.
- The biochemistry method 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 the polymorphism of plasma proteins, such as milk or blood, which provides information on the diversity of populations.
- The monosome method uses hybridization of somatic cells as the 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 you 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, as well as to trace the variability of the population when applying various selection options.
What is selection?
Breeding is a science that studies methods for creating new varieties and hybrids of plants, as well as animal breeds. The theoretical basis of selection is genetics.
The purpose of science is to improve the qualities of an organism or to obtain in it the properties necessary for a person by influencing heredity. With the help of selection, new species of organisms cannot be created. 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 in the characteristics of the body;
- increase productivity and productivity;
- increasing the resistance of organisms to diseases, pests, changes in climatic conditions.
A feature is the complexity of science. It is closely related to anatomy, physiology, morphology, systematics, ecology, immunology, biochemistry, phytopathology, crop production, animal husbandry and many other sciences. Significant knowledge is about fertilization, pollination, histology, embryology and molecular biology.
Achievements of modern selection allow you to manage the heredity and variability of living organisms. The importance of genetics for selection and medicine is reflected in the targeted control of the continuity of qualities and the possibilities of obtaining hybrids of plants and animals to meet human needs.
Selection development stages
Since ancient times, man has been engaged in breeding and selection of plants and animals for agricultural purposes. But such work was based on observation and intuition. The development of selection and genetics took place almost simultaneously. Consider the stages of selection:
- During the period of the development of plant growing and animal husbandry, selection began to have a mass character, and the formation of capitalism led to selective work at the industrial level.
- At the end of the 19th century, the German scientist F. Ahard conducted a study and planted sugar beet quality to increase productivity. English breeders P. Shiref and F. Galleta studied wheat varieties. In Russia, the Poltava Experimental Field was established, where varietal composition of wheat was studied.
- Selection as a science began to develop in 1903, when a selection 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 of cultural purpose, 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 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 were created. Modern research pays attention to obtaining high productivity in hybrids and resisting biotic and abiotic stressors.
Breeding methods
Genetics considers the patterns of transmission of hereditary information and how to manage such a process. In the selection, knowledge obtained from genetics is used, and other methods are used to evaluate organisms.
The main ones are:
- Selection method. In selection, natural and artificial (unconscious or methodological) selection is applied. A specific organism (individual selection) or their group (mass selection) can also be selected. The 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. The method distinguishes intraspecific (crossing occurs within one species) and interspecific hybridization (crossing of different species). Inbreeding allows you to consolidate hereditary properties while reducing the viability of the body. If outbreeding is carried out in the second or subsequent generations, the breeder receives high-yielding and resistant hybrids. It was established that with distant crossbreeding, the offspring are barren. Here, the importance of genetics for selection is expressed in the possibility of studying genes and influencing the fecundity of organisms.
- Polyploidy is the process of increasing chromosome sets, which allows you to achieve fertility in infertile hybrids. It is noted that some cultivated plants after polyploidy have a higher birth rate than their related species.
- Induced mutagenesis is an artificially induced process of mutations in the body after processing it with a mutagen. After the mutation ends, the breeder receives information about the influence of the factor on the body 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 allows you to isolate and study genes, to manipulate them with the aim of improving the qualities of organisms and breeding new species.
Plants
In the process of studying the growth, development and allocation of beneficial properties of plants, genetics and selection are closely interrelated. Genetics in the field of plant life analysis deals with the study of 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 particular organism.
- Control of plant signaling systems.
- Gene expression.
- Mechanisms of interaction between cells and plant tissues.
Breeding, in turn, ensures the creation of new or improving the quality of existing plant species based on 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 plant new qualities in plants that can be useful in various areas of human life, for example, in medicine or cooking. Also, knowledge about genetic characteristics allows you to get new varieties of crops that can grow in other climatic conditions.
Thanks to genetics in breeding, the method of crossing and individual selection is used. The development of the science of genes allows the use in breeding of methods such as polyploidy, heterosis, experimental mutagenesis, chromosomal and genetic engineering.
Animal world
Animal breeding and genetics are sections of the sciences that study the developmental characteristics of the animal kingdom. 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 humans.
Since ancient times, people have been selecting animals that, for example, are more suitable for use in agriculture or hunting. Of great importance for breeding are household attributes and the exterior. Thus, animals of economic purpose are evaluated by the appearance and quality of their offspring.
The use of genetic knowledge in breeding allows you to control the offspring of animals and their necessary qualities:
- resistance to viruses;
- increase in milk yield;
- size and physique;
- climate tolerance;
- fertility;
- offspring sex;
- elimination of hereditary disorders in posterity.
Animal breeding has spread not only in order to meet the primary human nutritional needs. Today you can observe many domestic breeds of animals bred artificially, as well as rodents and fish, such as guppies. Breeding and genetics in animal husbandry use such methods: hybridization, artificial insemination, experimental mutagenesis.
Breeders and genetics often face the problem of non-crossbred species among the first generation of hybrids and a significant decrease in the fertility of offspring. Modern scientists are actively addressing such issues. The main objective of scientific work is to study the patterns of compatibility of gametes, the fetus, and the mother’s body at the genetic level.
Microorganisms
Modern knowledge about selection and genetics allows us 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 trait and cannot be transferred to another organism. But studies have shown that bacterial DNA can be successfully introduced into plant chromosomes. Thanks to this process, the qualities inherent in bacteria or the 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 is carried out in a shorter time, compared with crop and livestock. This is due to the rapid multiplication and change of generations of microorganisms. Modern methods of selection and genetics - the use of mutagens and hybridization - have allowed the creation of microorganisms with new properties:
- mutants of microorganisms are capable of over-synthesis of amino acids and increased formation of vitamins and provitamins;
- mutants of nitrogen-fixing bacteria can significantly accelerate plant growth;
- bred yeast organisms - unicellular fungi and many others.
Breeders and genetics use these mutagens:
- ultraviolet;
- ionizing radiation;
- ethyleneimine;
- nitrosomethylurea;
- the use of nitrates;
- acridine paints.
For the effectiveness of the mutation, frequent treatment of the microorganism with small doses of mutagen is used.
Medicine and biotechnology
What is common in the importance of genetics for selection and medicine is that in both cases, science allows us to study the heredity of organisms and their immunity. Such knowledge is important for controlling pathogens.
The study of genetics in medicine allows you to:
- prevent the birth of children with genetic defects;
- to carry out the prevention and treatment of hereditary pathologies;
- to study the influence of the environment on heredity.
For this, the following methods are used:
- genealogical - the study of the family tree;
- twin - matching twin pair;
- cytogenetic - research of chromosomes;
- biochemical - allows you to identify mutant alleys in DNA;
- dermatoglyphic - analysis of the skin pattern;
- modeling and others.
2 , . . .
(, ) , , , . : , , , . : , .
Genetics and selection are sciences that are inextricably linked. Breeding work largely depends on the genetic diversity of the original number of organisms. It is these sciences that provide knowledge for the development of agriculture, medicine, industry and other areas of human life.