The cell cycle, or cell-division cycle, is the series of events that take place in a cell leading to its division and duplication (replication).The cell cycle consists of four distinct phases: G1 phase, S phase (synthesis), G2 phase (collectively known as interphase) and M phase (mitosis).
G1 = growth and preparation of the chromosomes for replication;
S = synthesis of DNA and duplication of the centrosome;
G2 = preparation for mitosis or M phase
M = mitosis and cytokinesis.