When the chromatin is extended and viewed under a microscope, the structure resembles beads on a string. Each of these tiny beads is a called a nucleosome and has a diameter of approximately 11 nm.

The DNA (red) is wound around two sets of core histone proteins (green) to form a kind of bead on a string. The H1 histone protein clamps the DNA into place where it enters and exits a bead.

When the chromatin is extended and viewed under a microscope, the structure resembles beads on a string. Each of these tiny beads is a called a nucleosome and has a diameter of approximately 11 nm.