Question

In DNA segment of six coils, 22 bp are linked by two hydrogen bonds. How many cytosine bases would be present

• A. 22
• B. 38
• C. 44
• D. 76

Answer 1

Answer: (B)

38

Since, one complete turn of the double helix has 10 base pairs, 6 coils of DNA will have 10x6= 60 base pairs.
According to the question, there are 22 base pairs with two hydrogen bonds which mean that out of total 60 base pairs in that DNA segment, the number of A-T pairs is 22;
the number of adenine = 22 and the number of thymine = 22;
Thus, number of G-C pairs = 60-22 = 38;
number of guanine = 38 and number of cytosine = 38;
So the correct answer is option B.