Sunday, February 8, 2009

Chromatin is a mass of genetic material composed of DNA and proteins that condense to form chromosomes in eukaryotic cell division. Chromatin is located in the cell's nucleus. The major components of chromatin are DNA and histone proteins, although many other chromosomal proteins have prominent roles too.

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, and to serve as a mechanism to control expression and DNA replication. Chromatin contains genetic material-instructions to direct cell functions. Changes in chromatin structure are affected by chemical modifications of histone proteins such as methylation and acetylation, and by non-histone, DNA-binding proteins.