DNA Packaging

The DNA double helix in a typical mammalian cell is roughly 2.2 metres long, yet it must fit inside a nucleus only about a micrometre (10^-6 m) across; the 2.2 m figure is simply the total number of base pairs multiplied by the distance between consecutive base pairs. To achieve this enormous size reduction without breaking or tangling, the DNA must be condensed through successive levels of coiling and supercoiling, assisted by specific proteins -- a process that differs somewhat between prokaryotes, …