Myofilament cross bridges form when which two structures bond?

• A. globular actin and troponin
• B. troponin and tropomyosin
• C. myosin tails and myosin heads
• D. myosin heads and globular actin

Answer: (D)

Verified step by step guidance

1. Understand the structure of a sarcomere, the basic unit of a muscle's striated muscle tissue, which includes thick and thin filaments.
2. Identify the components of the thick filament, primarily composed of myosin molecules, which have a tail and a head region.
3. Recognize the components of the thin filament, which is primarily composed of actin, along with regulatory proteins troponin and tropomyosin.
4. Learn that during muscle contraction, the myosin heads bind to specific sites on the globular actin molecules, forming cross bridges.
5. Understand that the formation of these cross bridges is crucial for the sliding filament theory, which explains how muscles contract by the sliding of actin over myosin.