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.

Question

Quizplus · Accepted Answer

The defect causes the myosin heads to bind ADP irreversibly, preventing the release of ADP and the subsequent binding of ATP, which is necessary for the detachment of myosin from actin. This results in the myosin heads being irreversibly cross-bridged with the actin binding sites, leading to paralysis.

A Group of Rats Are Bred in a Laboratory to Study