Question

A circular double-stranded DNA molecule contains 4200 base pairs. In solution, DNA is in a B-form helix, with about 10.5 base pairs/turn. The DNA has 12 superhelical turns. What is its superhelix density

Answer 1

The correct answer is - 3 × 10⁻²

Step-by-step explanation:

first find LKo = length of BDNA/ 10.5 bp/turn

= 4200/10.5

= 400

now calculate Δ LK= LK - LKo

ΔLK = 412-400

ΔLK = 12

now, superhelix density = ΔLK/LKo

⇒ 12/400 = 0.03

= 3×10⁻²

Thus, the correct answer is - 3 × 10⁻²