Question

A double stranded DNA molecule with $6390$ base pairs long will have the following number of turns:

• A. $639$
• B. $63.9$
• C. $6.39$
• D. $31.95$

Answer 1

The correct option is A $639$

In a DNA double helix, $10$ base pairs are present in 1 turn. Thus, 6390 base pairs will be present in $1/10\times 6390=639\text{turns}$