Question

The activities in the cell cycle occur during specific phases. In which phase of the cell cycle is DNA replicated?
A) Mitosis
B) G1 phase
C) G2 phase
D) S phase

Answer 1

S phase is the period during which DNA replication occurs.

The division cycle of most eukaryotic cells is divided into four discrete phases: M, G1, S, and G2. M phase (mitosis) is usually followed by cytokinesis.

Answer 2

Answer:

In the cell cycle, the replication of DNA occurs in the S-phase.

Explanation:

As we have learnt, the cell cycle can be defined as a series of cyclic events that occur during the lifetime of the cell, involved in its growth and developments.

The cycle can be divided into the Interphase (resting and preparation) and M-phase (division) -

Interphase can further be divided into -

• G₁ phase – it is the phase of the cell where the cell is metabolically active and continues to grow. We recollect that DNA replication doesn't occur here. This is also the first phase of the interphase.
• S phase – this is the most vital phase, wherein DNA replication takes place. We also recollect here that the chromosome number remains constant throughout this phase. More importantly, the division of the centrioles takes place.
• G₂ phase - here, the cellular contents necessary for the multiplication and division of the cell are produced, thereby making the cell prepared for the process of cellular division.

This is then followed by the M phase, which consists of 5 sub-phases -

• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis

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