Nucleosome Core

3D Model

Nucleosomes are the basic repeating units that form the eukaryotic chromatin, that after a series of folding, form a chromosome. The X-ray crystal structure of the nucleosome core particle of chromatin shows in atomic detail how the histone protein octamer is assembled and how 146 base pairs of DNA are organized into a superhelix around it.

This complex is often compared to thread wrapped around a spool.

Source