The term “genetics” was proposed in 1905 by W. Batson.
Genetics is a science that studies the laws of heredity and variability of organisms.
Heredity is the property of organisms to transmit structural features, physiological properties and the nature of individual development to descendants.
Variability is the ability of living organisms to change their characteristics.
In its development, genetics went through a number of stages.
People have been interested in heredity for a very long time. With the development of agriculture, the applied science of selection was formed, which was engaged in the creation and formation of new breeds of animals and plant varieties. But the breeders could not explain the mechanisms of transmission of traits to descendants.
The first stage in the development of genetics is the study of heredity and variability at the organismic level.
This stage is associated with the works of G. Mendel. In 1865, in his work “Experiments on plant hybrids”, he described the results of his research on the patterns of inheritance of traits in peas.
G. Mendel established the discreteness (separateness) of hereditary factors and developed a hybridological method for studying heredity.
Discreteness of heredity lies in the fact that individual properties and characteristics of the organism develop under the control of hereditary factors, which do not mix during the fusion of gametes and the formation of a zygote, but during the formation of new gametes are inherited independently of each other.
In 1909 W. Johannsen named these factors genes.
The significance of G. Mendel’s discoveries was appreciated only after his results were confirmed in 1900 by three biologists independently of each other: H. de Vries in Holland, K. Correns in Germany and E. Cermak in Austria. This year is considered the year of the emergence of the science of genetics.
Mendelian laws of heredity laid the foundation for the theory of the gene, and genetics became a rapidly developing branch of biology.
In 1901-1903. de Vries put forward the mutational theory of variability, which played an important role in the further development of genetics.
The second stage in the development of genetics is the study of the patterns of inheritance of traits at the chromosomal level.
The relationship was established between Mendelian laws of inheritance and the distribution of chromosomes in the process of cell division (mitosis) and maturation of germ cells (meiosis).
The study of the structure of the cell led to the clarification of the structure, shape and number of chromosomes and helped to establish that genes are sections of chromosomes.
In 1910-1911. American geneticist T.G. Morgan and his collaborators carried out research on the patterns of inheritance in Drosophila flies. They found that genes are arranged in a linear order on chromosomes and form linkage groups.
Morgan also established the patterns of inheritance of sex-linked traits.
These discoveries made it possible to formulate the chromosomal theory of heredity.
The third stage in the development of genetics is the study of heredity and variability at the molecular level.
At this stage, the relationship between genes and enzymes was studied and the theory “one gene – one enzyme” was formulated: each gene controls the synthesis of one enzyme, and the enzyme controls one biochemical reaction.
In 1953, F. Crick and J. Watson created a model of a DNA molecule in the form of a double helix and explained the ability of DNA to double itself. The mechanism of variability became clear: any deviations in the structure of a gene, once arising, are subsequently reproduced in daughter DNA strands.
These positions have been confirmed by experiments. The concept of a gene was clarified, the genetic code was deciphered and the mechanism of biosynthesis was studied. Methods for the artificial production of mutations were developed and with their help new valuable plant varieties and strains of microorganisms were created.
In recent decades, genetic engineering has been formed – a system of techniques that allows you to synthesize a new gene or isolate it from one organism and introduce it into the genetic apparatus of another organism.
In the last decade of the 20th century, the genomes of many simple organisms were deciphered. At the beginning of the 21st century (2003), a project to decipher the human genome was completed.
Today there are databases of the genomes of many organisms. The presence of such a human database is of great importance in the prevention and investigation of many diseases.