The contractile constituent of cytoskeleton is

Options

A. Microtubules
B. Intermediate filaments
C. Microfilaments
D. Microfibrils

Answer

To solve the question "The contractile constituent of cytoskeleton is," we will analyze the components of the cytoskeleton and identify which one is responsible for contractile functions.

### Step-by-Step Solution:

1. **Identify the Components of the Cytoskeleton**:
The cytoskeleton is made up of three main components:
- Microtubules
- Intermediate filaments
- Microfilaments

2. **Analyze Microtubules**:
Microtubules are polymers of tubulin protein. They form a hollow cylindrical structure and are primarily involved in providing structural support and facilitating intracellular transport. They are **not contractile** in nature.

3. **Analyze Intermediate Filaments**:
Intermediate filaments are composed of various proteins such as desmin and vimentin. They provide mechanical support to the cell and help maintain its shape. However, they do not have contractile properties, making them **not contractile**.

4. **Analyze Microfilaments**:
Microfilaments are polymers of actin protein. They are known for their role in muscle contraction, cell motility, and various cellular movements. Microfilaments are indeed the **contractile constituents** of the cytoskeleton, as they are involved in processes such as cytokinesis and amoeboid movement.

5. **Consider Microfibrils**:
Microfibrils are different from the components of the cytoskeleton. They are primarily found in plant cell walls and are made of cellulose and glycoproteins. Therefore, they are **not relevant** to the question.

6. **Conclusion**:
Based on the analysis, the correct answer to the question is **Microfilaments** (option C), as they are the contractile constituents of the cytoskeleton.

### Final Answer:
The contractile constituent of the cytoskeleton is **Microfilaments**.

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