What are the types of chromatin?

The two types of chromatin are known as euchromatin and heterochromatin. Euchromatin is loosely wrapped in DNA and is actively involved in transcription. Euchromatin is composed of repeating units of nucleosomes that are up to 11 mm in diameter. The core of these nucleosomes consists of pairs of four proteins: H3, H2A, H2B, and H4. The euchromatin changes to heterochromatin under the process of DNA repair or replication. In contrast to euchromatin, heterochromatin is highly condensed and is typically not transcribed. The heterochromatin is localized around the nucleolus and is separate from the euchromatin.