LOCUS (Latin locus the place) — the location of a gene in the relevant genetic structure of a cell (a chromosome, a plasmid, etc.). Sizes of separate L. are defined by amount of the genetic material (i.e. the size of a fragment of molecule DNA) which is contained in this or that gene and also features its structural funkts. organizations. As a result of changes — mutations (see) separate points (websites) of L. there can be various mutant forms — alleles (see) this gene (see). In cells of diploid organisms (including and the person) identical (homologous) L. pair chromosomes can be busy or identical (a homozygous state), or various (a heterozygous state) with alleles of the same gene. Each cellular structure containing genetic material (a chromosome, a mitochondrion, a plasmid) bears a certain number L., located linearly and making one linkage group. Localization and sequence of separate L. in a linkage group define with the help tsitol, and genetic methods of the analysis in the course of drawing up genetic maps of chromosomes, mitochondrions, bacterial plasmids, etc.
Bibliography: N. P. Genetik's tanks of the person (heredity and pathology), page 120, etc., M., 1978; D at and N and N. P N. General genetics, page 14, etc., M., 1976.
V. P. Shchipkov.