The DNA double helix wraps around a central core of eight histone molecules to form a single nucleosome. A second histone (H1 in the illustration) fastens the DNA to the nucleosome core. (Modified from Access Excellence)
How DNA is coiled and coiled again is shown in the series of drawings below. The DNA double helix is about 2 nm in width (and unspecified length). By the time the DNA double helix is fully condensed in the late prophase chromosome it has been thickened by a factor of nearly a 1000 times.
Modified from Curtis, Biology page 183
- A Microscopists' View of Chromosome Organization
- Nucleosomes - Molecular Genetics
- Nucleosomes - general information
- DNA repair within nucelosomes
Modified Dec. 6 2002