Final answer:
Step 1 of DNA replication involves the unwinding of the DNA double helix at the origin of replication, the action of DNA helicase in breaking hydrogen bonds between base pairs, and the stabilization of the single-stranded DNA by single-strand binding proteins.
Step-by-step explanation:
Step 1 of DNA Replication: The first step in DNA replication is crucial for the accurate duplication of the cell's genetic information prior to cell division. DNA unwinds at the origin of replication, a specific sequence on the chromosome where the replication process begins. An enzyme called DNA helicase breaks the hydrogen bonds between the base pairs, resulting in the formation of a replication fork. This unwinding creates two single-stranded DNA templates for the next stage of replication. Additionally, single-strand binding proteins stabilize the unwound DNA strands to prevent rewinding, and topoisomerase relieves the tension from DNA unwinding to prevent supercoiling ahead of the replication fork. This step sets the stage for the cells to create two complete copies of DNA, each containing one original and one new strand, a process termed semiconservative because each new DNA molecule conserves one of the original strands.