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Chromatin

the ordered and organized complex of DNA, protein, and sometimes RNA, that forms the chromosome

Chromatin is the complex combination of DNA and proteins that makes up chromosomes.[1][2] It is found inside the nuclei of eukaryotic cells.

Chromatin is divided into heterochromatin (condensed) and euchromatin (extended) forms.[3][4] Heterochromatin is composed mostly of satellite DNA tandem repeats. The active components of chromatin are DNA and histone proteins, although other proteins also occur.[5] The functions of chromatin are:

DNA packaging into chromosomes

Chromatin definitionsEdit

  1. Simple and concise definition: Chromatin is a macromolecular complex of a DNA macromolecule and protein macromolecules (and RNA). The proteins package and arrange the DNA and control its functions in the cell nucleus.
  2. The DNA + histone = chromatin definition: The DNA double helix in the cell nucleus is packaged by special proteins termed histones. The formed protein/DNA complex is called chromatin. The basic structural unit of chromatin is the nucleosome.

ReferencesEdit

  1. Van Holde K.E. 1989. Chromatin. New York: Springer-Verlag. ISBN 0-387-96694-3
  2. Cooper, Geoffrey M. 2000. The Cell: a molecular approach. 2nd ed, Chapter 4.2 Chromosomes and Chromatin
  3. "Chromatin Network Home Page". Retrieved 2008-11-18.
  4. Dame R.T. (2005). "The role of nucleoid-associated proteins in the organization and compaction of bacterial chromatin". Mol. Microbiol. 56: 858–70. doi:10.1111/j.1365-2958.2005.04598.x. PMID 15853876. 
  5. 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.