Cell cycle, illustration. The cell cycle, or cell-division cycle, is the cycle of events that occurs in a cell resulting in its division into two daughter cells. In the G1 phase (Gap 1) the cell grows. During the S phase (Synthesis) DNA replication occurs. In the G2 phase (Gap 2) the cell continues to grow, before entering the M phase (mitosis) where it divides into two daughter cells which continue the cycle. The whole cycle is divided into two main stages: interphase, incorporating G1, S and G2, and the mitotic (M) phase.