Which of the DNA Sequences is Complementary to 5' CGTAAGTA

Question

Which of the DNA sequences is complementary to 5' CGTAAGTA 3'
A) 5' TACTTACG 3'
B) 5' GCATTCAT 3'
C) 5' ATGAATGC 3'
D) 5' CGTAAGTA 3'

Accepted Answer

The complementary base pairing rules state that adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). Therefore, to find the complementary sequence to 5' CGTAAGTA 3', we need to replace each base with its complementary base. 
C will be replaced with G, G with C, T with A, and A with T. This gives us the sequence 5' TACTTACG 3', which is Option A.