Final answer:
DNA gyrase, also known as topoisomerase II, relieves the tension caused by supercoiling during DNA replication by breaking and reforming the DNA's phosphate backbone. Its action makes the DNA more accessible for replication by preventing excessive supercoils.
Step-by-step explanation:
DNA gyrase, also known as topoisomerase II, is an enzyme that plays a critical role in the process of DNA replication. During replication, unwinding the DNA helix is necessary for the replication machinery to access the genetic information. However, unwinding the double helix causes supercoiling, which, if not managed, can create tension in the DNA molecule and potentially disrupt the replication process. DNA gyrase relieves this supercoiling tension by making targeted breaks in the DNA's phosphate backbone, thereby allowing the DNA to be unwound without creating excessive supercoils. The enzyme then reforms these breaks after the tension has been relieved. This action essentially allows the DNA to be more accessible for replication and other cellular processes.