What is the role of topoisomerase II during DNA replication?

Topoisomerase II plays a crucial role during DNA replication by alleviating the strain that arises from the overwinding of DNA ahead of the replication fork. As the DNA helicase unwinds the double helix to allow for the synthesis of new strands, it creates tension in the adjacent sections of DNA. This tension can lead to supercoiling, which can impede the progress of replication if not managed.

Topoisomerase II addresses this problem by creating temporary cuts in the sugar-phosphate backbone of the DNA strands. This allows the unwound DNA to rotate and relieve the torsional strain. Once the tension is reduced, the enzyme reconnects the DNA strands, ensuring that the replication process can continue smoothly.

In contrast to other choices, topoisomerase II does not initiate transcription, add RNA primers, or produce multiple copies of DNA directly; its primary function is specifically to manage DNA topology during replication, thereby facilitating the overall process of DNA synthesis.