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During the contraction of a vertebrate skeletal muscle fiber, calcium ions A. break cross-bridges as a cofactor in hydrolysis of ATP. B. bind with troponin, changing its shape so that the myosin-binding sites on actin are exposed. C. transmit action potentials from the motor neuron to the muscle fiber. D. spread action potentials through the T tubules.

Respuesta :

Muscle contraction is defined as the activation of tension-generating sites within muscle fibers.

Contraction of a vertebrate skeletal muscle fiber is initiated when calcium ion binds to the troponin, a complex fibre protein.

What breaks the cross-bridge in muscle contraction?

ATP is critical for muscle contractions because it breaks the myosin-actin cross-bridge, freeing the myosin for the next contraction.

What is happening to the cross bridges during a skeletal muscle contraction?

After the power stroke, ADP is released; however, the cross-bridge formed is still in place, and actin and myosin are bound together. ATP can then attach to myosin, which allows the cross-bridge cycle to start again and further muscle contraction can occur.

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