Question

The centriole undergoes duplication during:

• A. Prophase
• B. S-phase
• C. Metaphase
• D. G2 phase

Answer 1

The correct option is B

S-phase

The correct option is B:

Explanation of the correct option:

1. The cell cycle is the process by which a cell duplicates its genome, synthesizes other cell parts, and eventually splits into two daughter cells.
2. Despite the fact that cell proliferation (in terms of cytoplasmic expansion) is a continuous process, DNA synthesis happens just once during the cell cycle.
3. There are two primary phases to the cell cycle: M Phase and Interphase
4. The M Phase is the time when a cell divides or undergoes mitosis, while the interphase is the time between two successive M phases.
5. The interphase takes up more than 95% of the cell cycle's time.
6. The interphase is further broken into three phases:
   1. G1 phase (Gap 1)
   2. S phase (Synthesis)
   3. G2 phase (Gap 2)
7. The G1 phase is the time period between mitosis and the start of DNA replication. The cell is metabolically active and expands continually during the G1 phase, but it does not duplicate its DNA.
8. The S phase, also known as the synthesis phase, is the time when DNA is synthesized or replicated.
9. In animal cells, DNA replication begins in the nucleus during the S phase, while the centriole duplicates in the cytoplasm.

Explanation of the incorrect option:

Option A:

1. Following the S and G2 phases of interphase, prophase is the initial stage of mitosis.
2. The onset of chromosomal material condensation characterizes prophase.

Option C:

1. The second phase of mitosis begins when the nuclear envelope completely disintegrates, and the chromosomes are distributed throughout the cell's cytoplasm.
2. Chromosome condensation is complete at this point, and they may be seen clearly under the microscope. This is the stage at which the morphology of chromosomes may be investigated the most easily.

Option D:

Proteins are synthesized in preparation for mitosis during the G2 phase, while cell development continues.

Final answer: The centriole undergoes duplication during S-phase.