Question

The graph shows the changes in DNA content during various phases (1 to 4) in a typical cell. Identify the phase and select the correct option.

• A. 1-G${}_2$, 2-G${}_1$, 3-S, 4-M
• B. 1-M, 2-G${}_2$, 3-S, 4-G${}_1$
• C. 1-G${}_1$, 2-S, 3-G${}_2$, 4-M
• D. 1-M, 2-G${}_1$, 3-S, 4-G${}_2$

Answer 1

The correct option is C 1-G${}_1$, 2-S, 3-G${}_2$, 4-M

The cell cycle is a four-stage process consisting of gap 1 (G${}_1$), synthesis (S), gap 2 (G${}_2$) and mitosis (M), which a cell undergoes as it grows and divides. During G${}_1$​ phase, DNA content is 2C. S phase is marked by replication of DNA and the amount of DNA per cell is doubled (4C). During G${}_2$​ phase, synthesis of RNA and proteins takes place and still the amount of DNA is 4C. During mitosis (M phase), DNA content gets equally distributed among two daughter cells and DNA again equal to the parent cell (2C). Hence, correction option is 1-G${}_1$, 2-S, 3-G${}_2$, 4-M.