Question

The correct sequence of phases of cell cycle is:

• A. M→G1→G2 →S
• B. G1→G2 →S→M
• C. S→G1→G2→ M
• D. G1→ S→G2→ M

Answer 1

The Correct Option is D

The cell cycle is a series of events that take place in a cell leading to its division and duplication. It is a crucial process for cell growth and reproduction. The correct sequence of the phases of the cell cycle is necessary to maintain proper cellular function and development.

The correct sequence of the phases of the cell cycle is:

1. G1 Phase (Gap 1): This is the first gap phase where the cell grows in size and synthesizes mRNA and proteins (known as histones) that are required for DNA synthesis. It provides the raw materials for the next step in the cell cycle.
2. S Phase (Synthesis): During this phase, DNA replication occurs. Each chromosome creates an identical copy during this phase, resulting in two sister chromatids for each chromosome.
3. G2 Phase (Gap 2): This is the second gap phase following DNA synthesis. The cell continues to grow and prepares for the mitotic phase. It produces the necessary proteins and organelles for the next step.
4. M Phase (Mitosis): This phase involves the division of the cell’s nucleus and is followed by cytokinesis, where the cell splits into two cells. This results in the distribution of identical chromosomes to each daughter cell.

With this understanding, we can deduce that the correct sequence of phases of the cell cycle is G1→ S→G2→ M. The other options list the phases in incorrect order:

• M→G1→G2→S: Incorrect as it begins with M phase and places S phase last.
• G1→G2→S→M: Incorrect as it reverses the order of the G2 and S phases.
• S→G1→G2→M: Incorrect as it starts with S phase, which should follow G1.

Therefore, the correct answer is G1→ S→G2→ M.