G1(Gap 1) phase: It starts immediately after the previous division. Therefore, it is called as first growth phase or post-division gap phase. It is a resting phase. Synthesis of RNA, proteins and membranes takes place. No DNA synthesis takes place during this phase. The cell grows in volume.
S(Synthesis) phase: It is the period during which DNA synthesis occurs, i.e. replication of chromosomal DNA takes place. At the end of S phase, each chromosome has two DNA molecules and a duplicate set of genes.
G2(Gap 2) phase: It is the last part of interphase and occurs just before the new cell division. Hence, it is also called as second growth phase or pre-division gap phase. During G2 phase, synthesis of RNA and proteins continue and the nuclear volume increases.
