Question

In which stage DNA duplication occurs?

• A. G${}_1$
• B. G${}_2$
• C. S
• D. In all stages

Answer 1

The correct option is C S

Cell cycle occurs in four well-defined stages; G${}_1$, S phase, G${}_2$ and M phase. The S (synthesis) phase is characterized by DNA replication to produce copies for both daughter cells; the DNA amount of cell is doubled. The G${}_2$ phase (G stands for the gap between divisions) is characterized by synthesis of new proteins are and the cell enlargement. The M phase (mitosis) is marked by the breakdown of maternal nuclear envelope and segregation of sister chromosomes to opposite poles of the cell, which are then surrounded by the nuclear membrane, and formation of two daughter cells through cytokinesis. Now each daughter cell enters a waiting period (G${}_1$), the duration of which varies according to cell types, in which RNA and protein synthesis occurs. The correct answer is C.