title: Higher-order structure of human mitotic chromosomes.
abstract: From observations on the partial disintegration of isolated human metaphase chromosomes we propose that human metaphase chromatids have a rather simple organization based on the folding and coiling of a long, regular, hollow cylindrical structure with a diameter of about 4000 A. This cylindrical structure, the unit fiber, is postulated to be a super-solenoid formed by the coiling of a 300 A solenoid, itself composed by coiling the basic string of nucleosomes. The structure of a human chromatid would thus be a hierarchy of helices, the contraction ratio of each coil, in ascending order of size, being approximately 7, 6, 40, and 5. This model appears to explain the estimated mass/unit length and accounts for many of the known features of human mitotic chromatids.
mesh_terms: D002875:Chromosomes / Q000502:physiology / Q000648:ultrastructure*; D004247:DNA; D005333:Fetus; D005347:Fibroblasts; D006801:Humans; D008854:Microscopy, Electron; D008938:Mitosis; D009690:Nucleic Acid Conformation
chemical_list: D004247:DNA
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