Final answer:
DNA helicases are enzymes that unwind DNA by breaking the hydrogen bonds between the base pairs. They separate the two strands of DNA at the replication fork during DNA replication.
Step-by-step explanation:
The enzymes that unwind DNA are called DNA helicases. These enzymes are responsible for separating the two strands of DNA at the replication fork during DNA replication.
They use ATP energy to break the hydrogen bonds between the base pairs, allowing the DNA strands to unwind.