Adding nucleotides onto a growing DNA strand during DNA replication in cells occurs in ____.
A) the 5' -3' direction for the leading strand and the 3' -5' direction on the lagging strand
B) either the 5' -3' direction or the 3' -5' direction on both strands, depending on where replication begins
C) the 5' -3' direction only
D) the 3' -5' direction for the leading strand and the 5' -3' direction on the lagging strand
E) the 3' -5' direction only

Question

Adding nucleotides onto a growing DNA strand during DNA replication in cells occurs in ____.
A) the 5' ->3' direction for the leading strand and the 3' ->5' direction on the lagging strand
B) either the 5' ->3' direction or the 3' ->5' direction on both strands, depending on where replication begins
C) the 5' ->3' direction only
D) the 3' ->5' direction for the leading strand and the 5' ->3' direction on the lagging strand
E) the 3' ->5' direction only

Quizplus · Accepted Answer

DNA polymerase, the enzyme responsible for adding nucleotides, can only add nucleotides to the 3' end of a DNA strand, making DNA synthesis proceed in the 5' -> 3' direction on both the leading and lagging strands.

Adding Nucleotides onto a Growing DNA Strand During DNA Replication