A Group of Rats Are Bred in a Laboratory to Study

question 27

Multiple Choice

A group of rats are bred in a laboratory to study muscle function. This group possesses a genetic defect that causes the myosin heads to bind ADP irreversibly. The rats are entirely paralyzed. Which of the following correctly explains the impact of the defect on the muscle?

• A)ATP won't bind to the myosin heads, preventing the actin binding site of the thick filament from being revealed.
• B)Because ADP is permanently bound, the myosin heads can never bind to the actin binding sites of the thin filament.
• C)Because ADP is permanently bound, the myosin heads will be irreversibly cross-bridged with the actin binding sites of the thin filament.
• D)ATP won't bind to the myosin heads, causing the thin filament to be constantly pulled in the power stroke of contraction.