[https://en.wikipedia.org/wiki/Histone Histones] are a family of basic, positively charged proteins that associate with DNA inside the nucleus to help condense the DNA into [https://en.wikipedia.org/wiki/Chromatin chromatin] <ref name="Histones"> Histones | Learn Science at Scitable https://www.nature.com/scitable/definition/histone-histones-57</ref>. The nuclear DNA is wrapped around the histone in order to fit in the nucleus. [https://en.wikipedia.org/wiki/Nucleosome Nucleosomes] are chromatin beads made up of DNA wrapped around eight histone proteins, or a [https://en.wikipedia.org/wiki/Histone_octamer histone octamer] <ref name="Histones" />. Four different examples of modifying histones including [https://en.wikipedia.org/wiki/Histone_acetylation_and_deacetylation Histone acetylation, Histone deacetylation], [https://en.wikipedia.org/wiki/Histone_methylation Histone methylation] and [https://en.wikipedia.org/wiki/Demethylase Histone demethylation] <ref name="Histones" />.