A schematic illustration to show the basic architecture of nucleosome.

<p>Nucleosomes form the fundamental repeating units of eukaryotic chromatin (upper panel), each of them consists of approximately 147 base pairs of DNA wrapped in 1.67 left-handed superhelical turns around a histone octamer consisting of 2 copies each of the core histones H2A, H2B, H3, and H4 (lower panel).