When does DNA get replicated?

DNA replication occurs during the S phase of the cell cycle. Here are the steps:

1. Initiation: The DNA double helix unwinds at the origin of replication, forming a replication fork. This is facilitated by various proteins including helicase, which breaks the hydrogen bonds between the base pairs.

2. Elongation: DNA polymerase adds new nucleotides to the 3' end of the existing DNA strand, following the base pairing rules (A with T, C with G). This process occurs in the 5' to 3' direction.

3. Termination: Once the entire DNA molecule has been replicated, the process is terminated. The two new DNA molecules each contain one old (original) strand and one new strand. This is known as semi-conservative replication.

This process ensures that each new cell has an exact copy of the DNA.