What is Chromatin?
'''Chromatin''' is the complex combination of [[DNA]] and [[protein]]s that makes up [[chromosome]]s.<ref>Van Holde K.E. 1989. ''Chromatin''. New York: Springer-Verlag. {{ISBN|0-387-96694-3}}</ref><ref>Cooper, Geoffrey M. 2000. ''The Cell'': a molecular approach. 2nd ed, Chapter 4.2 [https://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=cooper&part=A618#A620 Chromosomes and Chromatin]</ref> It is found inside the [[cell nucleus|nuclei]] of [[Eukaryote|eukaryotic]] [[cell (biology)|cells]]. Chromatin is divided into '''heterochromatin''' (condensed) and '''euchromatin''' (extended) forms.<ref>{{cite web|url=http://chromatin.net/|title=Chromatin Network Home Page.|language=en|access-date=2008-11-18|archive-date=2011-08-13|archive-url=https://web.archive.org/web/20110813142546/http://chromatin.net/|url-status=dead}}</ref><ref> {{cite journal |author=Dame R.T.|title=The role of nucleoid-associated proteins in the organization and compaction of bacterial chromatin|journal=Mol. Microbiol.|volume=56|pages=858–70|year=2005|issue=4|pmid=15853876|doi=10.1111/j.1365-2958.2005.04598.x|s2cid=26965112}} </ref> Heterochromatin is composed mostly of [[satellite DNA]] [[tandem repeat]]s. The active components of chromatin are DNA and [[histone]] proteins, although other proteins also occur.<ref>Van Holde K.J. ''et al'' 1995. Elements of chromatin structure: histones, nucleosomes, and fibres, p. 1-26. In S.C.R. Elgin (ed) Chromatin structure and gene expression. IRL Press at Oxford University Press, Oxford.</ref> The functions of chromatin are: *to package DNA into a smaller volume to fit in the cell *to strengthen the DNA to allow [[mitosis]] and [[meiosis]] *to control [[DNA replication]] and [[gene expression]]. How this works is not yet clear. [[File:Chromatin Structures.png|thumb|center|500px|DNA packaging into chromosomes]] == Chromatin definitions == # '''Simple and concise definition:''' Chromatin is a macromolecular complex of a DNA [[macromolecule]] and protein macromolecules (and RNA). The proteins package and arrange