Cohesin blocks local mixing of compact active genome domains, study finds

The human genome, extending roughly two meters in length, is compacted within a cell nucleus only about 10 micrometers in diameter. This extreme condensation is achieved by winding DNA around histone proteins to create nucleosomes, which then assemble into the larger macromolecular complex known as chromatin. The hierarchical organization of chromatin enables the genome to be efficiently packaged while still permitting regulated access to genetic information.

For many years, chromatin has been classified into two principal states: euchromatin, characterized by a relatively open configuration that supports active transcription, and heterochromatin, which adopts a more compact structure associated with gene repression. This binary framework continues to guide research into genome function and regulation, underscoring the balance between DNA accessibility and structural stability within the nucleus.