What is the function of topoisomerase in DNA replication?

Topoisomerase plays a critical role during DNA replication by relieving the torsional stress that builds up ahead of the replication fork. When the DNA double helix unwinds to allow replication to occur, it causes strain and supercoiling in the DNA strand ahead. Topoisomerase cuts one or both strands of the DNA to allow the strands to unwind, thus preventing supercoiling and allowing replication to proceed smoothly. This function is essential because excessive supercoiling can hinder the progression of the replication machinery.

While sealing gaps in the DNA, creating primers, and unzipping the DNA are important functions in the overall process of DNA replication, they are handled by other enzymes and proteins, such as DNA ligase, primase, and helicase, respectively. Topoisomerase specifically addresses the supercoiling issue, making it a unique and vital component of the replication process.