[Cell determination and differentiation: a concept of gene clusters]

This paper formulates a conception of cluster organization of the genetic material, responsible for cell determination and differentiation in multicellular organisms. According to this conception, gene controlling each particular stage of these processes are functionally integrated via genes-activators into gene groups (clusters) of different levels of hierarchy. Besides, some hypotheses of molecular mechanisms providing the action of these gene groups have been put forward. Attempts were made to elucidate some phenomena of cell differentiation, specifically a drop or a complete loss of dividing ability in highly specialized cells, in addition to a property of the cell to remember the history of its own development inside the organism, and to inherit the ancestor's direction of differentiation. Attention was paid to a mechanism (originating from this conception) of the emergency of malignant tumors, which means that cells giving rise to tumors are known to evade primarily their involvement in the process of further specialization. Besides, mechanisms of a molecular supply of positional information are examined. Phylogenetic aspects concerning the standing of the fragment of genetic apparatus controlling cell specialization, and the development of its inner hierarchy that involves subordination of some clusters to other ones.