Question

If one strand of DNA sequence is - 5'-GAATTG-3' - then the sequence of the opposite strand is

• A. 5'-CAATTC-3'
• B. 5'-CTTAAC-3'
• C. 5'-GAATTG-3'
• D. 5'-GTTAAG-3'
• E. 5'-TAATTC-3'

Answer 1

The correct option is A 5'-CAATTC-3'

A DNA strand is complementary. This means adenine pairs with thymine and cytosine pairs with guanine in the opposite strand. The given strand has a sequence 5'-GAATTG-3'. Hence the complementary strand will have a sequence 5'-CAATTC-3'. Thus the correct answer is option A.