"The interphase portion of the cell cycle is relatively long compared to mitosis. Interphase consists of three stages: first gap (G1), synthesis (S) and second gap (G2). The cell replicates DNA only in the S phase. Before the cell can transition from G1 to S, it must clear the G1 checkpoint."
"The S Phase of Interphase. The S phase of a cell cycle occurs during interphase, before mitosis or meiosis, and is responsible for the synthesis or replication of DNA. ... The most important event occurring in S phase is the replication of DNA."
