Chromatin is divided into heterochromatin (condensed) and euchromatin (extended) forms. The major components of chromatin are DNA and histone proteins, although other proteins also occur. 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 serve as a mechanism to control expression and DNA replication.
Chromatin contains genetic material: instructions to direct cell functions. Changes in chromatin structure are one way the action of genes is controlled.