Figure 24.

Schematic structure of chromatin showing the nucleosome units, inside which DNA pairs are wrapped around histone proteins. Close chromatin (called heterochromatin) is densely packed (left side of the figure) and transcription cannot occur. For transcription to occur, chromatin must be open, yielding the so-called euchromatin (right part of the figure). Condensing DNA into chromosomes (top right part of the figure) prevents DNA tangling and damage during cell division. Courtesy: National Human Genome Research Institute (https://www.genome.gov/genetics-glossary/Nucleosome (accessed on 27 November 2024)).