NEETZoologyLocomotion and Movement
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): During the cross-bridge cycle of muscle contraction, the cross-bridge between actin and myosin is broken when a new ATP molecule binds to the myosin head. Reason (R): The hydrolysis of ATP into ADP and inorganic phosphate is directly responsible for breaking the cross-bridge. In the light of the ab
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
C. (A) is correct but (R) is not correct
Step-by-step solution
Assertion (A) is correct: During the cross-bridge cycle, after the power stroke occurs and the myosin head releases ADP and Pi, a new ATP molecule binds to the myosin head. This binding causes the cross-bridge to detach from the actin filament. Reason (R) is incorrect: The hydrolysis of ATP into ADP and Pi does not break the cross-bridge. Instead, ATP hydrolysis provides the energy to return the myosin head to its energized or 'cocked' state, preparing it for the next cycle of cross-bridge formation. It is the mere