Euchromatin's a lightly packed form of chromatin that's rich in gene concentration, and's often (but not always) under active transcription. Unlike heterochromatin, it's found in both eukaryotes and prokaryotes. Euchromatin comprises the most active portion of the genome within the cell nucleus. Structure The structure of euchromatin's reminiscient of an unfolded set of beads along a string, where those beads represent nucleosomes. Nucleosomes consist of eight proteins known as histones, with ap… (More on Euchromatin)