Nucleosome formation condenses DNA by approximately sevenfold and 30-nm fiber formation condenses DNA by a further 100-fold. How long will a 450,000 bp segment of linear DNA be after compaction to a 30-nm fiber?

Question

Quizplus · Accepted Answer

The initial length of the DNA can be calculated assuming the length of DNA per base pair is approximately 0.34 nm. So, 450,000 bp * 0.34 nm/bp = 153,000 nm. After nucleosome formation, this is condensed approximately sevenfold, resulting in 153,000 nm / 7 ≈ 21,857 nm. The further compaction into a 30-nm fiber condenses it by about 100-fold, leading to 21,857 nm / 100 ≈ 218.57 nm. The closest answer to this calculation is ~2,000 nm (D).

Nucleosome Formation Condenses DNA by Approximately Sevenfold and 30-Nm Fiber