Final answer:
Topoisomerase helps manage the torsional stress on DNA during replication by breaking and re-joining the phosphate backbone, which prevents supercoiling and ensures a smooth replication process.
Step-by-step explanation:
Topoisomerase plays a critical role in DNA replication by relieving the torsional stress that is caused by the unwinding of the double helix. During the replication process, when the double helix unwinds to allow the synthesis of new DNA strands, the DNA ahead of the replication fork becomes supercoiled. This tension would make DNA unwinding and replication impossible if not resolved. Topoisomerase acts by breaking and subsequently rejoining the DNA's phosphate backbone, which allows the helix to spin and relax. This process helps to prevent supercoils from becoming too tight and risking damage to the DNA during replication.
Moreover, topoisomerase is not confined to the replication fork but can also operate along the length of the chromatin to manage torsional stress as it arises. In this way, topoisomerase ensures the smooth continuation of DNA replication by managing the physical strains imposed upon the DNA molecule as it unwinds and doubles.