The energy that is released by the hydrolysis of ATP by actin is used for :

Options

A. actin filaments assembly
B. actin filaments disassembly
C. actin-myosin assembly
D. actin-myosin disassembly

Answer

To solve the question regarding the energy released by the hydrolysis of ATP by actin, we can break down the process step by step:

### Step-by-Step Solution:

1. **Understanding ATP Hydrolysis**:
- ATP (adenosine triphosphate) is a molecule that stores energy in its high-energy phosphate bonds. When ATP is hydrolyzed (i.e., when it reacts with water), it releases energy.

2. **Role of Actin and Myosin in Muscle Contraction**:
- In muscle cells, two primary contractile proteins are involved: actin and myosin. Myosin has a bulbous head that can bind to actin filaments.

3. **ATP Binding and Hydrolysis**:
- The myosin head has both an ATP binding site and an actin binding site. When ATP binds to the myosin head, it is hydrolyzed to ADP (adenosine diphosphate) and inorganic phosphate (Pi). This hydrolysis releases energy.

4. **Formation of Actomyosin Complex**:
- The energy released from ATP hydrolysis is used for the conformational change in the myosin head, allowing it to bind to the actin filament. This forms the actomyosin complex.

5. **Muscle Contraction Mechanism**:
- The formation of the actomyosin complex is crucial for muscle contraction. The myosin head pulls the actin filament, leading to muscle shortening and contraction.

6. **Conclusion**:
- Therefore, the energy released by the hydrolysis of ATP by actin is primarily used for the formation of the actomyosin complex, which is essential for muscle contraction.

### Final Answer:
The energy released by the hydrolysis of ATP by actin is used for the formation of the actomyosin complex, which is essential for muscle contraction.

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