During muscle contraction , hydrolysis of ATP results in a change in the .

Options

A. structure of the myofibrils
B. conformation of myosin
C. conformation of actin
D. structure of the sarcoplasmic reticulum

Answer

To solve the question "During muscle contraction, hydrolysis of ATP results in a change in the:", we need to analyze the role of ATP in muscle contraction and identify which structure is affected by its hydrolysis.

### Step-by-Step Solution:

1. **Understanding Muscle Contraction**:
- Muscle contraction involves the interaction between two key proteins: actin and myosin. These proteins form cross-bridges that enable muscle fibers to contract.

2. **Role of ATP**:
- ATP (adenosine triphosphate) is the energy currency of the cell. During muscle contraction, ATP is hydrolyzed to ADP (adenosine diphosphate) and inorganic phosphate (Pi), releasing energy.

3. **Myosin and Actin Interaction**:
- Myosin heads bind to actin filaments to form cross-bridges. The binding of ATP to myosin is crucial for the muscle contraction cycle.

4. **Hydrolysis of ATP**:
- When ATP is hydrolyzed, it provides the energy necessary for the myosin head to change its conformation. This change is essential for the myosin head to pull on the actin filament, leading to muscle contraction.

5. **Identifying the Change**:
- The question asks what specifically changes due to ATP hydrolysis. The hydrolysis of ATP primarily causes a change in the conformation (shape) of the myosin head, allowing it to pivot and pull the actin filament.

6. **Conclusion**:
- Based on the analysis, the correct answer is that the hydrolysis of ATP results in a change in the **conformation of myosin**.

### Final Answer:
**B. Conformation of myosin**