During which phase of the cell cycle does DNA replication occur?

DNA replication occurs during the S phase of the cell cycle, which stands for "Synthesis." This is a crucial period where the cell prepares for division by duplicating its genetic material. During the S phase, each chromosome is replicated to produce two identical sister chromatids, ensuring that when the cell eventually divides, each daughter cell receives an exact copy of the DNA.

In the context of the cell cycle, the S phase follows the G1 phase, where the cell grows and synthesizes proteins and organelles but does not yet replicate its DNA. It precedes the G2 phase, which is another growth period where the cell prepares for mitosis, checking for DNA damage and ensuring all genetic material is correctly replicated. Finally, the M phase is the actual process of mitosis, where the cell divides, but no DNA replication occurs during this phase.