Most cells of the human body typically contain DNA having about 6,000,000,000 base pairs, which would measure nearly 2 m in length if stretched out end to end. Yet this genomic DNA is packaged into cellular nuclei that are roughly 10 micrometers, or 0.00001 m, in width. This remarkable compaction is aided by the wrapping of the genome into a complex between DNA and proteins known as “chromatin.”