Identify the correct statement

Options

A. 'F' actin a polymer of 'G' actin molecules
B. Heavy meromyosin forms tail
C. Light meromyosin forms head
D. Each light meromyosin has two bindings sites

Answer

To solve the question of identifying the correct statement regarding the components of muscle contraction, we will analyze each of the provided statements step by step.

### Step-by-Step Solution:

1. **Understanding F-actin and G-actin**:
- F-actin, or filamentous actin, is a polymer made up of G-actin (globular actin) monomers.
- G-actin molecules are the building blocks (monomers) that come together to form the filamentous structure of F-actin.
- **Conclusion**: The statement that "F-actin is a polymer of G-actin molecules" is correct.

2. **Analyzing Heavy Myosin**:
- Heavy myosin (HMM) is a large molecule formed from fragments of myosin 2, which serves as the monomer.
- Heavy myosin is known to form the head structure of the myosin protein.
- **Conclusion**: The statement that "heavy myosin forms head" is correct.

3. **Analyzing Light Myosin**:
- Light myosin is often associated with forming the tail part of the myosin protein.
- The statement that "light myosin forms head" is incorrect because light myosin does not form the head structure; it forms the tail.
- **Conclusion**: The statement that "light myosin forms head" is incorrect.

4. **Binding Sites on Myosin**:
- Each head of the myosin molecule has two binding sites, which are crucial for muscle contraction.
- The statement that "each light myosin has two binding sites" is incorrect because the binding sites are located on the head of the myosin, not on the light myosin tail.
- **Conclusion**: The statement that "each light myosin has two binding sites" is incorrect.

5. **Final Conclusion**:
- After analyzing all statements, the only correct statement is that "F-actin is a polymer of G-actin molecules."

### Final Answer:
The correct statement is: **F-actin is a polymer of G-actin molecules.**

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