Question

A new DNA strand elongates in only one direction because ___________.

A. DNA polymerase can only add nucleotides to the 3' end
B. DNA polymerase can only add nucleotides to the 5' end
C. RNA polymerase can only add nucleotides to the 3' end
D. RNA polymerase can only add nucleotides to the 5' end

Answer 1

The new DNA strand elongates in only one direction because DNA polymerase can only add nucleotides to the 3' end.

Step-by-step explanation:

The correct answer is A. DNA polymerase can only add nucleotides to the 3' end.

DNA polymerase reads the template strand in the 3' to 5' direction and adds nucleotides only in the 5' to 3' direction. The leading strand is synthesized in the direction of the replication fork. Replication on the lagging strand occurs in the direction away from the replication fork in short stretches of DNA called Okazaki fragments.