Final answer:
The tension created by unwinding the DNA helix during replication is positive supercoiling, which is resolved by the enzyme topoisomerase by cutting and rejoining the DNA strands.
Step-by-step explanation:
During DNA replication, the unwinding of the helix causes tension that leads to positive supercoiling ahead of the replication fork. This tension is resolved by the enzyme topoisomerase. The topoisomerase enzyme works by cutting and then rejoining the DNA strands, allowing the helix to relax and continue the replication process without damaging the DNA molecule.
The tension created ahead of the replication fork during DNA replication is due to negative supercoiling. This occurs as the DNA strands unwind and separate. The enzyme responsible for resolving this tension is topoisomerase. Topoisomerase breaks and reforms the DNA's phosphate backbone ahead of the replication fork, relieving the pressure caused by the supercoiling.