What is the first step of DNA replication?

The first step of DNA replication is the unwinding of the DNA double helix by the enzyme helicase. Helicase breaks the hydrogen bonds between the complementary base pairs, separating the two DNA strands and creating two single-stranded templates. This unwinding occurs at specific regions called origins of replication. Once the DNA is unwound, single-strand binding proteins (SSBs) bind to the single strands to prevent them from reannealing, allowing replication to proceed.