Which of the following does NOT occur during skeletal muscle contraction?

• A. Calcium concentration in the sarcoplasm increases.
• B. The I bands shorten, and H zones disappear.
• C. Myosin heads bind to actin.
• D. Calcium binds to myosin heads.
• E. ATP is hydrolyzed.

Answer: (D)

Verified step by step guidance

1. Understand the process of skeletal muscle contraction, which involves several key steps: calcium release, binding of myosin to actin, and ATP hydrolysis.
2. Calcium ions are released from the sarcoplasmic reticulum into the sarcoplasm, increasing calcium concentration, which is essential for muscle contraction.
3. Calcium binds to troponin, not myosin heads, causing a conformational change that moves tropomyosin away from actin's binding sites, allowing myosin heads to bind to actin.
4. During contraction, the sarcomere shortens, which leads to the shortening of the I bands and disappearance of the H zones as actin and myosin filaments slide past each other.
5. ATP is hydrolyzed by myosin heads, providing the energy required for the power stroke that pulls actin filaments toward the center of the sarcomere.