Question

If one strand, of double stranded DNA, consists of the sequence 3'-ATTCGTAC-5', then the complementary sequence must be

• A. 5'-UAAGCAUG-3'
• B. 3'-TAAGCATG-5'
• C. 5'-TAAGCATG-3'
• D. 5'-UAAGCATG-3'

Answer 1

Answer: (C)

5'-TAAGCATG-3'

The two strands of DNA are complementary to each other such that the adenine residues on one strand form double hydrogen bonds with the thymine residues on the other strand and vice versa. Similarly, the guanine residues form triple hydrogen bonds with the cytosine residues and vice versa. This is called the complementary base pairing. The two strands are anti-parallel. Therefore, if one strand has a 3'-ATTCGTAC-5' sequence, then the other strand would be 5'-TAAGCATG-3'.

Hence, the correct answer is 5'-TAAGCATG-3'