The cell replicates its DNA during the S phase (Synthesis phase) of the cell cycle. This phase is part of interphase, where the cell synthesizes a complete copy of its DNA in the nucleus and duplicates the centrosomes, preparing for cell division.

Details about the S phase:

• DNA replication occurs so that each chromosome consists of two sister chromatids by the end of this phase.
• The amount of DNA in the cell doubles during this phase, although the number of chromosomes remains the same.
• Other phases in interphase include G1 (cell growth) and G2 (preparation for mitosis), but DNA replication is specific to the S phase.
• After S phase, the cell proceeds to mitosis (M phase), where it divides into two daughter cells.