What is the first step in replication?
The first step in replication is the unwinding of the DNA double helix. To understand this process, let's break it down step by step:
1. Unwinding: In the nucleus of a cell, the DNA molecule consists of two strands that are tightly wound around each other in a shape called a double helix. Replication begins by the separation of these two strands, which is achieved by an enzyme called helicase. Helicase breaks the hydrogen bonds between the base pairs (A-T and G-C) along the DNA molecule, causing the two strands to separate.
Helicase does this by traveling along the DNA molecule and progressively breaking the hydrogen bonds between the base pairs. This process creates a replication bubble where the two strands separate.
To recap, the first step in replication is the unwinding of the DNA double helix through the action of the enzyme helicase.