Question

The number of base pairs in each turn of Z-DNA and B-DNA helices respectively is

• A. 9 and 11
• B. 12 and 10
• C. 10 and 13
• D. 12 and 11

Answer 1

The correct option is B 12 and 10

B-DNA is physiologically the most important form of DNA. The double helical secondary structure model of DNA described by Watson and Crick was the B-DNA. As per the original model, it contains 10 bp per turn but later measurements showed that it contains 10.5 base pairs per turn. Z DNA is the zigzag DNA. It is left handed helix. There are 12 base pair per turn, with a rise of 0.38 nm per base pair.
So, the correct answer is option B.