Allele and non-allelic genes

The meaning of genetics

With the discovery of the foundations of genetics, science has acquired a vast base of new studies of the substratum of evolution - the genetic code. It is in it that information about all past and forthcoming changes for the development of the organism is laid.

The ratio of heredity and variability allows you to save only the best qualities, and instead of failing to acquire new ones, improving the structure and contributing to a victory in natural selection.

Basic concepts of genetics

In modern genetics, the chromosomal inheritance theory is adopted, according to which the main morphological substrate is the chromosome - a structure from a condensed complex of DNA (chromatin), from which information is read during the synthesis of proteins.

Genetics is based on several concepts: a gene (a region of DNA coding for a particular single sign), a genotype and a phenotype (a set of genes and body traits), gametes (sex cells with a single set of chromosomes) and zygotes (diploid cells).

Genes, in turn, are classified into dominant (A) and recessive (a) depending on the predominance of one feature over another, allelic (A and a) and non-allelic genes (A and B). Allelics are located on identical sections of chromosomes and encode one feature. Non-allelic genes are absolutely the opposite of them: they are located on different sites and code different signs. However, despite this, non-allelic genes have the ability to interact with each other, giving rise to entirely new traits. On 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 - different (Aa).

Mechanism and patterns of gene interaction

Forms of interaction of genes among themselves studied American geneticist TH Morgan. The results of his research he expounded in the chromosome theory of heredity. According to her, the genes included in one chromosome are inherited together. Such genes are called linked and form the so-called. Clutch groups. In turn, within these groups, there is also a recombination of genes through crossing-over - exchange of chromosomes by different sites among themselves. At the same time, it is absolutely logical and proven that the genes located immediately after each other are not subjected to separation in 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 was called "incomplete cohesion of genes." If we talk about this in more detail, then the interaction of allelic genes occurs in three simple schemes: complete dominance with the production of a pure dominant trait, incomplete dominance to obtain an intermediate feature, and codomination with inheritance of both characters. Non-allelic genes are inherited more complicated: according to the schemes of complementarity, polymorphism or epistasis. In this case, both traits will be inherited, but in varying degrees.