Interaction of genes

The gene is the structural unit of information transmitted by inheritance. It is a specific section of the DNA molecule (sometimes RNA). Interaction of genes ensures the transfer of elementary signs of parental organisms to offspring.

Each gene defines a specific feature that does not depend on others. They are able to interact. This is possible due to the fact that linked gene inheritance occurs. When combined into a genotype, they act as a system. The main relations between them are dominance and recessivity.

The human genotype is thousands of characters (system) that fit in only 46 chromosomes. Each of them contains a huge number of genes (not less than 30 thousand).

The degree of development of a specific feature can be due to the influence of not one gene, but a whole series, which are interconnected in a free manner. This interaction of genes is commonly called a polymer (multisyllabic). By this mechanism, the skin color, hair and hundreds of other traits are inherited.

Thanks to this number of genes, vital activity and the development of definitive organisms, consisting of various types of specialized differentiated cells, are provided. In humans, about 200 cell types have been identified that have additional subdivisions into a number of more specialized functional and morphological types of cells.

The combination of genes in one chromosome is determined by the term gene-linking. All the genes belonging to the same clutch group are inherited together when gametes are formed.

In different clutch groups, the number of genes is not the same. Dihybrid interaction is characterized by the fact that such a linkage does not obey the laws of Mendel. However, full adhesion is rare. As a rule, all four phenotypes are represented in the offspring.

Allelic and non-allelic interaction of genes are distinguished . Alleles are forms of the same gene.

Allelic is the interaction of genes entering into one allelic pair. The manifestation of the sign is determined not only by the relationship of dominance, but also by the number of genes in the genotype.

Allelic genes are able to create such connections as complete dominance (when in the phenotype of heterozygotes there is a product of only one gene) and incomplete (the heterozygote phenotype differs from the phenotype of homozygotes by dominant and recessive, taking the mean (intermediate) value with respect to them. The interaction of allelic genes, when heterozygotes in the phenotype have a product of both.

Non-allelic is the joint effect of two (several) non-allelic genes. Can be expressed in the form of an epistatic, complementary, polymeric or modifying interaction.

The interaction of non-allelic genes can take place in different ways, so several types are distinguished.

Complementary - the interaction of self-miming genes in one genotype and causing the manifestation of any one characteristic.

Polymeric is the additive effect of a number of non-allelic genes on the formation of a certain feature, which causes a variational continuous series in quantitative terms. Polymerism is cumulative and non-cumulative. In the first case, the manifestation of the trait is determined by the number of dominant alleles of polymeric genes that are contained in the genotype. In the second case, the degree of development of the trait is determined only by the presence of dominant alleles and does not depend on their number.

Epistatic - the suppression of one gene by the dominant allele of another, non-allelic to the first. Or suppression of the action of the dominant and recessive allele in the hypostatized gene by the recessive allele of the epistatic allele in the homozygous state.

Complementary - the symptom develops under the mutual action of 2 dominant genes, which individually do not cause development of the trait.

Modifying - a change in the action of the main genes by non-allelic modifiers in relation to them. One gene can act as the main one in controlling the development of a certain trait and modifier in relation to the development of another trait.

Interaction of genes is always observed, when several genes influence the formation of a certain state of any sign of the organism.