Listed are four enzymes involved in DNA replication1. DNA polymerase III 2. Primase 3. DNA ligase 4. DNA polymerase I. The correct order of action of these enzymes in lagging strand DNA synthesis is

Question

Quizplus · Accepted Answer

The lagging strand is synthesized in the opposite direction of the replication fork and is synthesized in short fragments called Okazaki fragments.

1. Primase synthesizes a short RNA primer at the beginning of each Okazaki fragment.
2. DNA polymerase III extends the RNA primer by adding DNA nucleotides in the 5' to 3' direction. It synthesizes the entire Okazaki fragment.
3. DNA polymerase I replaces the RNA primers with DNA nucleotides and repairs any gaps left between the Okazaki fragments.
4. DNA ligase joins the Okazaki fragments together, forming a continuous strand.

Therefore, the correct order is 2 (Primase), 1 (DNA polymerase III), 4 (DNA ligase), 3 (DNA polymerase I), which corresponds to option B.

Listed Are Four Enzymes Involved in DNA Replication1