Final answer:
Helicase is responsible for unzipping the DNA helix at the origin of replication by breaking the hydrogen bonds between nucleotides, allowing DNA polymerase to access the DNA template and synthesize a new DNA strand.
Step-by-step explanation:
The primary responsibility of helicase during DNA replication is to separate the two strands of the DNA double helix. Helicase achieves this by breaking the hydrogen bonds between the nucleotide base pairs at the origin of replication. This process is critical to DNA replication because it provides single-stranded DNA templates that DNA polymerase uses to synthesize the new daughter strands.
After helicase unwinds the DNA, the resulting over-winding or supercoiling ahead of the replication fork is managed by topoisomerase which breaks and reforms the DNA's phosphate backbone thus relieving any built-up tension. Protective proteins known as single-stranded binding proteins stabilize the unwound DNA strands by binding to them, ensuring they stay apart and do not re-anneal prematurely. Additionally, primase synthesizes a short RNA primer that DNA polymerase relies on to begin the synthesis of the new DNA strand.