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A localized aggregation of histone and DNA that is evident when chromatin is in the uncondensed stage. SYN: nu body. [nucleo- + G. soma, body]
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nu·cleo·some -.sōm n any of the repeating globular subunits of chromatin that consist of a complex of DNA and histone and are thought to be present only during interphase
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nu·cleo·some (nooґkle-o-sōm) [nucleo- + -some] the primary structural unit of eukaryotic chromatin; a complex of histone and DNA seen with the electron microscope as one of the “beads on a string†characteristic of the partially unfolded chromatin in low ionic strength buffer. It comprises a segment of approximately 146 base pairs of DNA wrapped twice around an octamer core of two each of the histones H2A, H2B, H3, and H4, and is connected to each adjacent nucleosome by a short linker DNA segment. The nucleosomes are further compacted into a 30-nm diameter fiber, the structure of which remains controversial; the classic model describes it as a helical solenoid (q.v.).Medical dictionary. 2011.