Chromatin fibres duplication, Genetic material -4C, Histone protein synthesis, Membranous organelle duplication, DNA replication, centriole duplication.
How many of the above features are associated with synthesis phase of cell cycle ?

Options

A. Three
B. Five
C. Four
D. Six

Answer

To solve the question regarding the features associated with the synthesis phase (S phase) of the cell cycle, we will analyze each feature mentioned in the question step by step.

### Step-by-Step Solution:

1. **Chromatin Fibres Duplication**:
- Chromatin fibers themselves do not duplicate. Instead, during the S phase, DNA replication occurs, which results in the duplication of the genetic material. Therefore, this feature is **not associated** with the S phase.

2. **Genetic Material - 4C**:
- In the S phase, the DNA is replicated. If the parental cell has 2C amount of DNA, after replication during the S phase, the amount of DNA becomes 4C. This feature is **associated** with the S phase.

3. **Histone Protein Synthesis**:
- Histone proteins are crucial for DNA packaging. However, histone protein synthesis primarily occurs during the G2 phase, not during the S phase. Thus, this feature is **not associated** with the S phase.

4. **Membranous Organelle Duplication**:
- Most membranous organelles duplicate during the G1 phase of the cell cycle. Therefore, this feature is **not associated** with the S phase.

5. **DNA Replication**:
- DNA replication is the defining event of the S phase. This feature is **associated** with the S phase.

6. **Centriole Duplication**:
- Centrioles, which are involved in cell division, duplicate during the S phase. This feature is **associated** with the S phase.

### Summary of Features Associated with the S Phase:
- Associated with S phase:
- Genetic Material - 4C
- DNA Replication
- Centriole Duplication

- Not associated with S phase:
- Chromatin Fibres Duplication
- Histone Protein Synthesis
- Membranous Organelle Duplication

### Final Count:
Out of the six features listed, **three features** (Genetic Material - 4C, DNA Replication, and Centriole Duplication) are associated with the synthesis phase of the cell cycle.

### Answer:
**3 features are associated with the synthesis phase of the cell cycle.**

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