Question

In B-DNA, the distance between two base pairs is

• A. 3.4 Å
• B. 34 Å
• C. 0.34 Å
• D. 20 Å

Answer 1

The correct option is A 3.4 Å

In the B-DNA double helix, each strand appears like a helical staircase. Each step of ascent is represented by a pair of bases. At each step of ascent, the strand turns 36°. One full turn of the helical strand would involve ten base pairs or ten steps. The pitch is 34 Å and the rise per base pair is 3.4 Å.