[Three levels of structural organization of the eukaryotic chromosomes]

Three levels of structural organization of eukaryotic DNA in the cell nucleus are considered in this paper: (i) the chain of nucleosomes; (ii) the solenoidal or superbead (nucleomere) model of compactization of the nucleosomal fiber; (iii) the mode of suprasolenoidal DNP-packing--loops or domains. Recent results bearing on the relation of these three levels to functional activity of chromatin are also discussed.