What is the primary function of topoisomerases?

The primary function of topoisomerases is to change the amount of supercoiling in DNA. These enzymes play a crucial role in managing DNA topology during processes such as replication and transcription. When DNA is unwound, as occurs during replication, it can become tangled or generate excessive supercoiling ahead of the replication fork. Topoisomerases alleviate this tension by cutting the DNA strands, allowing them to rotate and relieve the supercoiling before rejoining the strands. This action is essential for maintaining the proper structure and function of the DNA, enabling smooth replication and transcription.

The other functions listed do not pertain to the role of topoisomerases. Synthesis of new DNA strands is primarily carried out by DNA polymerases, while degrading DNA molecules involves nuclease enzymes. While topoisomerases do play a role in transcription, their primary function is not to facilitate the binding of RNA polymerase but rather to manage DNA supercoiling, making option B the correct choice.