Nucleosome
Space-filling model of an intact Nucleosome (PDB ID 1aoi).
The nucleosome is the basic unit of structural organization of DNA in a chromosome.
A nucleosome is composed of almost two turns of DNA (purple) wrapped around a set of eight proteins called histones that is referred to as a histome octamer. Each histone octamer is composed of two copies each of the histone proteins H2A (blue) H2B (yellow), H3 (red), and H4 (green).