How many primers are required for the leading and lagging strands during DNA replication?

During DNA replication, the leading strand is synthesized continuously in the direction of the replication fork and requires a single short strand of RNA known as a primer to initiate DNA synthesis. This primer is crucial as DNA polymerase cannot begin synthesizing DNA from scratch; it requires a free 3' hydroxyl (OH) group to which it can add nucleotides.

On the lagging strand, however, DNA synthesis occurs in short bursts, producing discrete segments called Okazaki fragments, which are synthesized in the opposite direction of the replication fork. Each Okazaki fragment also requires a primer to provide the necessary 3' OH group for DNA polymerase to extend the new DNA strand. Since there are multiple Okazaki fragments produced along the lagging strand, each of these fragments necessitates its own separate primer.

Therefore, the correct response clearly indicates that one primer is required for the leading strand, while a distinct primer is needed for each individual Okazaki fragment on the lagging strand. This results in one primer for the leading strand and a number of primers equal to the number of Okazaki fragments on the lagging strand. This understanding highlights the difference in how the leading and lagging strands are synthesized during DNA replication.