ANATOMY

Detailed explanation-1: -As discussed later, the motor activity of myosin moves its head groups along the actin filament in the direction of the plus end. This movement slides the actin filaments from both sides of the sarcomere toward the M line, shortening the sarcomere and resulting in muscle contraction.

Detailed explanation-2: -So, the correct answer is ‘A-Band remains constant’.

Detailed explanation-3: -ATP and Muscle Contraction The motion of muscle shortening occurs as myosin heads bind to actin and pull the actin inwards. This action requires energy, which is provided by ATP. Myosin binds to actin at a binding site on the globular actin protein.

Detailed explanation-4: -In summary, myosin is a motor protein most notably involved in muscle contraction. Actin is a spherical protein that forms filaments, which are involved in muscle contraction and other important cellular processes.