Question

In animal cells the DNA synthesis occurs during phase of cell cycle

• A. G1
• B. G2
• C. S
• D. G0

Hint:

Associate "S" phase directly with "Synthesis" of DNA (Replication).
The amount of DNA doubles (from \(2\text{C}\) to \(4\text{C}\)) during this phase.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The eukaryotic cell cycle is divided into distinct, regulated phases (G1, S, G2, M) to ensure accurate cellular growth and genome duplication.

Step 2: Detailed Explanation:
Let us review the events in each phase of the cell cycle:
1. G1 (Gap 1) phase: Cell growth, protein synthesis, and metabolic preparation for DNA replication.
2. S (Synthesis) phase: The cell replicates its nuclear genomic DNA, doubling its DNA content. Histones are also synthesized during this phase.
3. G2 (Gap 2) phase: Final growth and checkpoint verification before mitosis.
4. G0 (Gap 0) phase: A quiescent, non-dividing state where cells exit the active cell cycle.
Therefore, DNA synthesis occurs exclusively during the S phase.

Step 3: Final Answer:
The correct option is 3, which corresponds to S.