During the cell cycle, cells grow, double their nuclear deoxyribonucleic acid (DNA) content through chromosome replication, and prepare for the next mitosis (chromosome separation) and cytokinesis (cytoplasm separation). In effect, the cell cycle is the proliferating cell's life history. Cells spend most of their time in interphase, the period between divisions, acquiring competence for division. For example, in the higher plant Arabidopsis thaliana at 23°C, meristematic cells are in interphase for eight hours but are in mitosis for only thirty minutes.

An idealized cell cycle, showing the order of mitosis (M), cytokinesis (C), postmitotic interphase (G1), DNA synthetic phase (S-phase), and postsynthetic interphase (G2). Major control points of the cell cycle at G1/S and G2/M are indicated as hatched rectangles. P34 (Cdc2 kinase) is shown bound to a cyclin at G2/M, where it exhibits catalytic activity (ﾀ) while cyclin degrades at M/G1 and...