The enzyme that unwinds or unzips the parent strand during DNA replication is helicase.

Here's how it works:

* Breaking Hydrogen Bonds: Helicase breaks the hydrogen bonds that hold the two strands of the DNA double helix together. This "unzips" the molecule, exposing the nucleotide bases.

* Creating a Replication Fork: The separation creates a Y-shaped structure called a replication fork, where new DNA strands can be synthesized.

* Moving Along the DNA: Helicase moves along the DNA strand, continuously unwinding it as replication proceeds.

Note: Helicase requires energy to break the hydrogen bonds, which it obtains from ATP.