|MoBio||Chromatin Structure||Chapter 3|
Chromatin is the substance which becomes visible chromosomes during cell division. Its basic unit is nucleosome, composed of 146 bp DNA and eight histone proteins. The structure of chromatin is dynamically changing, at least in part, depending on the need of transcription (see Chapter 4 Section G). In the metaphase of cell division, the chromatin is condensed into the visible chromosome. At other times, the chromatin is less condensed, with some regions in a Beads-On-a-String conformation.