Traditionally, chromatin is classified as either euchromatin or heterochromatin, depending on its level of compaction. Euchromatin has a less compact structure, and is often described as a 11 nm fiber that has the appearance of ‘beads on a string’ where the beads represent nucleosomes and the string represents DNA. In contrast, heterochromatin is more compact, and is often reported as being composed of a nucleosome array condensed into a 30 nm fiber. Read more..