Gene

GENE (from Greek gignomai - I become), a hereditary determinant; the term was introduced by Johannsen with the intention that it should contain "no hypothesis," and he contrasted it with the concept of a "hereditary trait." Being present in the organism, in every cell of the body, genes in some way influence the development of the organism, which is why, with different genes, the organism acquires different traits. It is probable that the gene acts chemically and, moreover, in the immediate vicinity of the cell in which it is located. If for some reason a gene is found only in a part of the organism, then the corresponding trait manifests only in that part. It is not yet possible to give a precise definition of the essence of the gene, and various geneticists define the gene differently. It has been proven that genes are located in chromosomes (see), arranged "linearly" along their length, firmly occupying specific places, and are likely parts or segments of chromosomes. The existence of a gene is discovered when it passes from one stable state to another via transgenation (see Mutation, Genovariations), which is usually accompanied by the appearance of a new hereditary trait, in accordance with which both the new and the original gene receive a name ("color gene," "hemophilia gene," etc.) and a symbol. If the newly emerged trait is recessive (see), then the new gene is designated by a lowercase letter (for example, a), and the original gene, accordingly, by an uppercase letter (A). According to the presence-absence theory, only genes for dominant traits really exist, while genes for recessive traits are merely an "absence," i.e., "nothing." According to the views of the Morgan school (Morgan), genes for recessive traits are also real, being merely qualitative changes of the genes for dominant traits. The original gene and the new one that arose from it are "allelomorphs" of each other. With the appearance of a new gene, usually one new, more noticeable trait arises, but careful study often reveals the change of many others, and the Morgan school admits that each gene influences all traits of the organism to varying degrees, and consequently, conversely, each trait depends to varying degrees on all genes present in the organism. Attempts have been made to count the number of genes in chromosomes and to measure them, but so far without significant results. Genes are very stable formations, and there are no methods yet for obtaining desired changes in them. However, it has been possible to significantly increase the variability of genes (the frequency of transmutations) with the help of X-rays and gamma-rays. Of enormous importance, however, is the property of genes to form the most diverse combinations with each other. Man can control this combination with the help of Mendelism (see). Based on the nature of the change produced by different genes in the organism, one distinguishes "major genes," "enhancers," "reducers," "distributors," "modifiers," lethal genes (see), "paired genes," "multiple genes," etc. The minimal but complete set of genes of a given species of organism (one of each gene) constitutes "one genome." The totality of an organism's genes constitutes its genotype (see). The totality of genes of a population (see) constitutes its "gene pool."