Centriole/centrosome replication occurs in

Options

A. Early prophase
B. `G_(1)-phase`
C. S-phase
D. `G_(0)-phase`

Answer

**Step-by-Step Solution:**

1. **Understanding Cell Cycle Phases**: The cell cycle consists of several phases: G1 (first gap), S (synthesis), G2 (second gap), and M (mitosis). Interphase includes G1, S, and G2 phases, where the cell prepares for division.

2. **Identifying the G1 Phase**: The G1 phase is the first phase of interphase. During this phase, the cell grows, synthesizes proteins, and produces organelles. It is crucial for the cell's normal functions and prepares the cell for DNA replication.

3. **Centrosome Replication**: The centrosome, which is essential for cell division, begins to replicate during the G1 phase. This is an important step as it prepares the cell for the upcoming DNA synthesis in the S phase.

4. **S Phase and G2 Phase**: In the S phase, the cell duplicates its DNA content. The G2 phase follows, where the cell continues to grow and prepares for mitosis. However, the replication of centrioles specifically occurs in the G1 phase.

5. **Conclusion**: Therefore, the correct answer to the question of when centriole/centrosome replication occurs is during the G1 phase of the cell cycle.

**Final Answer**: Centriole/centrosome replication occurs in the G1 phase.

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