Question

Which end of an RNA primer is nearest the replication fork on the lagging strand?

-3′ end
-5′ end
-either end

Answer 1

The end of an RNA primer is nearest the replication fork on the lagging strand is A. 3′ end

Step-by-step explanation:

The lagging strand is made up of short fragments called Okazaki fragments. Each Okazaki fragment requires a primer to initiate synthesis, which is an RNA primer. The RNA primer is synthesized in the 5' to 3' direction by the enzyme primase. The RNA primer is added at the 3' end of each Okazaki fragment, and then the DNA polymerase adds deoxyribonucleotides in the 5' to 3' direction.

The lagging strand is oriented in the 3' to 5' direction, opposite to the direction of fork movement. As the replication fork moves, a protein complex called the primosome moves along the lagging strand. The primosome contains several proteins, including the enzyme primase, which synthesizes the RNA primer. Therefore, the 3' end of the RNA primer is nearest the replication fork on the lagging strand. Therefore the correct answer is A. 3′ end