B-DNA which is right -handed double helix contains ______ base pairs per turn of the helix and each tum is _____ long .

Options

A. 10, 3.4 Å
B. 10, 34 Å
C. 11, 20 Å
D. 11, 34 Å

Answer

B

Explanation

In B-DNA, one turn of the helix has about `10` nucleotides on each strand of DNA. A turn occupies a distance of about `3.4` nm (`34 Å` or `3.4 xx10^(-9)m`) so that adjacent nucleotides or their bases are separated by a space of about `0.34 nm (0.34xx10^(-9)m or 3.4 Å)`.