ABSTRACT
The progression from one cell division to the next can be regarded as a cyclic process, the cell cycle. During this time the cell must replicate its contents and then organize the distribution of its components equally between two daughter cells. Except in the production of gametes (see Section C3) the nuclei of eukaryote cells divide by mitosis and in parallel with this the cytoplasm divides by cytokinesis. These processes are easily visualized in fixed or living cells. The period between two consecutive divisions is referred to as a cell cycle. The replication of DNA is accomplished during a period in the cell cycle known as the synthetic or S phase. The period preceding S phase is called G1 (gap 1), and the period between S phase and division is known as G2 (gap 2).
