Question

Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?

Answer 1

Answer:

D) 5'-ATGC-3' with 5'-GCAT-3'

Explanation:

In a double helix DNA, adenine always pairs with thymine and cytosine pairs with guanine. Also, the two strands of a double helix DNA are antiparallel, that is, the 5' end of one strand lies opposite to the 3' end of another strand.

Therefore, a DNA strand with base sequence 5'-ATGC-3' would have a complementary strand 5'-GCAT-3'.

Double stranded DNA: 5'-ATGC-3'                                          

                                      3' TACG 5'