The meaning of genetics
With the discovery of the foundations of genetics, science has acquired an extensive base of new research on the substrate of evolution - the genetic code. It is in it that information is laid down about all past and upcoming changes for the development of the organism.
The ratio of heredity and variability allows you to save only the best qualities, and instead of unsuccessful ones, acquire new ones, improving the structure and contributing to the victory in natural selection.
Basic concepts of genetics
In modern genetics, the chromosomal theory of inheritance is taken as the basis, according to which the main morphological substrate is the chromosome - a structure from a condensed DNA complex (chromatin), from which information is read in the process of protein synthesis.
Genetics is based on several concepts: gene (section of DNA encoding a specific single trait), genotype and phenotype (sets of genes and traits of an organism), gametes (sex cells with a single set of chromosomes) and zygotes (cells with a diploid set).
Genes, in theirIn turn, they are classified into dominant (A) and recessive (a) depending on the predominance of one trait over another, allelic (A and a) and non-allelic genes (A and B). Alleles are located on the same parts of the chromosomes and encode one trait. Non-allelic genes are absolutely opposite to them: they are located in different areas and encode different traits. However, despite this, non-allelic genes have the ability to interact with each other, giving rise to the development of completely new traits. According to the qualitative composition of allelic genes, organisms can be divided into homo- and heterozygous: in the first case, the genes are the same (AA, aa), in the other they are different (Aa).
Mechanism and patterns of gene interaction
The forms of gene interaction were studied by the American geneticist T. H. Morgan. He presented the results of his research in the chromosome theory of heredity. According to her, genes included in the same chromosome are inherited together. Such genes are called linked and form the so-called. clutch groups. In turn, within these groups, recombination of genes also occurs by crossing over - the exchange of chromosomes by different sections among themselves. At the same time, it is absolutely logical and proven that the genes located directly one after another are not subjected to separation during the process of crossing over and are inherited together.
If there is a distance between the genes, then the probability of separation exists - this phenomenon is called "incomplete linkage of genes." If we talk about this in more detail, thenthe interaction of allelic genes with each other occurs according to three simple schemes: complete dominance with obtaining a pure dominant trait, incomplete dominance with obtaining an intermediate trait, and codominance with inheritance of both traits. Non-allelic genes, on the other hand, are more difficult to inherit: according to the schemes of complementarity, polymerization, or epistasis. In this case, both traits will be inherited, but to a different extent.
