DNA replication occurs during the S phase (synthesis phase) of the cell cycle. This is the phase where the cell synthesizes a complete copy of its DNA in preparation for cell division, ensuring that each daughter cell receives an identical set of genetic information. Replication starts at specific locations in the DNA called origins of replication and follows a tightly regulated process to ensure it happens only once per cell cycle.
Key Points About When DNA Replicates
- DNA replication takes place in the S phase of the cell cycle, after the G1 phase.
- The initiation of replication is prepared in the G1 phase but activated in the S phase.
- The process ensures faithful copying of the entire genome before a cell divides.
- Replication occurs once and only once per cell cycle, preventing duplicate copying.
- In prokaryotes, replication starts at a single origin, while eukaryotes have multiple origins of replication.
Thus, DNA replication happens specifically during the S phase, which is part of the interphase of the cell cycle, prior to mitosis or cell division.
