Answer:
Explanation:
Four stages of a typical cell cycle The life cycle of eukaryotic cells can generally be divided into four stages and a typical cell cycle is shown in Figure 2.4.13 . When a cell is produced through fertilization or cell division, there is usually a lag before it undergoes DNA synthesis (replication). This lag period is called Gap 1 (G1), and ends with the onset of the DNA synthesis (S) phase, during which each chromosome is replicated. Following replication, there may be another lag, called Gap 2 (G2), before mitosis (M). Cells undergoing meiosis do not usually have a G2 phase. Interphase is as term used to include those phases of the cell cycle excluding mitosis and meiosis. Many variants of this generalized cell cycle also exist. Some cells never leave G1 phase, and are said to enter a permanent, non-dividing stage called G0. On the other hand, some cells undergo many rounds of DNA synthesis (S) without any mitosis or cell division, leading to endoreduplication. Understanding the control of the cell cycle is an active area of research, particularly because of the relationship between cell division and cancer.
