Question

How much DNA is wrapped around the histone octamer in a nucleosome?

Options

• Approximately 246 base pairs in 3 turns

• Approximately 146 base pairs in 1.65 turns

• Approximately 90 base pairs in 1 turn

• Approximately 200 base pairs in 2 turns

Answer 1

Approximately 146 base pairs of DNA wrap around the histone octamer in 1.65 turns to form the nucleosome core. Together with the linker DNA (20–90 base pairs) between nucleosomes, the total DNA per nucleosome unit is approximately 200 base pairs, and the resulting nucleosome fibre has a diameter of approximately 10 nanometres.