Chromosomes

Chromosomes, the most important component of the nucleus, sharply revealed in the process of karyokinesis due to their ability to be intensely stained by basic dyes. The totality of modern biological data forces us to consider chromosomes as carriers of hereditary properties, and the central point of karyokinesis to be the moment of precise distribution of maternal chromosomes between daughter cells. The most essential facts concerning chromosomes are as follows: 1) the law of individuality of chromosomes - their specific (generally speaking, very different and sometimes extremely bizarre) shape, inherent to each chromosome within one set; 2) the law of constancy in the number of chromosomes within a given species, with the most recent detailed research (Zhivago, Delia Valle) showing that this refers to statistical constancy, alongside which significant individual deviations from the average number of chromosomes appear in individual cells. The quantity and form of chromosomes in representatives of different, even closely related species differ considerably. The question of the individuality of chromosomes is closely connected with the question of their pre-existence during the interkinesis stage (between divisions); a series of facts, for example, the so-called gonomeria phenomena - the individual dissolution of chromosomes in separate vesicles during the telophase stage and their appearance from similar vesicles in the next prophase - make the existence of chromosomes in a latent form during interkinesis extremely probable. The question of the time of chromosome splitting is not fully clarified; most researchers believe that this process occurs very early - already at the prophase stage, and according to some opinions - even at the end of the preceding division. In physicochemical terms, chromosomes are in a state of dense gel. There are a number of hypotheses regarding their fine structure. The majority of researchers agree on the assumption that the most important element of chromosomes is the achromatin axial thread, along which areas of basic chromatin (chromomeres) are located. Thus, the cytological confirmation is obtained for the gene theory, which considers the hereditary capital of an organism as the sum of separate, independent traits collected in chromosomes (see Heredity).

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