title: Linking numbers and nucleosomes.
abstract: In considering supercoils formed by closed double-stranded molecules of DNA certain mathematical concepts, such as the linking number and the twist, are needed. The meaning of these for a closed ribbon is explained and also that of the writhing number of a closed curve. Some simple examples are given, some of which may be relevant to the structure of chromatin.
mesh_terms: D002843:Chromatin / Q000648:ultrastructure*; D004247:DNA; D008961:Models, Structural; D009690:Nucleic Acid Conformation
chemical_list: D002843:Chromatin; D004247:DNA