What organic substance is a nucleosome composed of?

Nucleosomes are the basic repeating units of chromatin which is a combination of DNA and proteins that make up the content's of a cell's nucleus. Nucleosomes are made of a histone octamer which is comprised of two of the following histones: H2A, H2B, H3, and H4. The histone octamer is bound and wrapped around approximately 146 base pairs of DNA and an additional H1 histone is added and is wrapped around 20 more base pairs.