Question

what occurs during the first step of dna replication? (1 point)
the two strands that will make up a dna double helix begin to chemically bind.
the enzyme rna polymerase starts to copy the dna sequence of a chromosome.
the enzyme helicase begins splitting apart the strands of a dna molecule.
a single strand of dna starts to combine with a single strand of rna.

Explanation:

DNA replication starts with the unwinding of the double - helix structure. Helicase is the enzyme that breaks the hydrogen bonds between the base pairs of the two DNA strands, separating them. RNA polymerase is involved in transcription (synthesis of RNA from DNA), not the first step of DNA replication. DNA strands combine with RNA strands during processes like transcription (not the first step of DNA replication), and DNA replication is about copying DNA, not binding new DNA strands at the start (the first step is unwinding, not binding).

Answer:

The enzyme helicase begins splitting apart the strands of a DNA molecule.