Refer to the following diagram of DNA complementary base pairing below. Which of the following bases would pair (from top to bottom) with the exposed 3´ end strand?
A) GACT
B) TCGA
C) AGCT
D) TAGC
E) ATCG

Question

Refer to the following diagram of DNA complementary base pairing below. Which of the following bases would pair (from top to bottom) with the exposed 3´ end strand? 
A) GACT 
B) TCGA 
C) AGCT 
D) TAGC 
E) ATCG

Quizplus · Accepted Answer

The 3´ end of the exposed strand is T, so it can only pair with A on the complementary strand. Then, the complementary strand reads AGC, so the next base in the exposed strand must be T to pair with A again. This pattern continues, giving the sequence TCGA. Therefore, the best choice is B.

Refer to the Following Diagram of DNA Complementary Base Pairing