Question

What is the role of ATP in muscle contraction and relaxation?

Multiple Choice

• It is hydrolyzed from the myosin head to attach to actin.

• All apply.

• It powers the Ca2+ pumps to return Ca2+ to the SR.

• It causes myosin head to detach from actin.

Answer 1

Answer:

Option B (All apply)

Explanation: ATP (Adenosine triphosphate) has a number of major functions to be performed in order to have the process of muscle contraction and relaxations in place. These functions are as summarized below;

a) A muscle is said to be contracted when the formation of actin-myosin complex takes place. The head of the myosin has an ATPase activity which can hydrolyze the ATP and using the energy released from the same, the myosin head can be attached to the active sites present on the surface of actin

b) The formation of actin-myosin complex takes place because of a major role played by the calcium ions. The calcium ions gets released from the sarcoplasmic reticulum and enters the sarcoplasm wherein it alters the shape of other proteins named troponin, and tropomyosin which then frees the surface of actin such that myosin can get bound there. Since calcium are divalent ions, their movement across the membrane of the sarcoplasmic reticulum would require ATP molecules and the energy released by them

c) Also, the ATP binding causes the myosin head to get detached from the actin such that the myosin head again hydrolyses the ATP and likewise the repeated cycle of muscle contraction and relaxation gets continued