In a laboratory experiment you have treated a muscle cell with a calcium channel blocker.The membrane still depolarizes,but the concentration of calcium never increases in the cytosol.Which of the following describes what will happen next?
A)Only one cross-bridge cycle will occur but no second cycle.
B)Binding of myosin to actin will take place.
C)Tropomyosin will continue to cover the myosin binding sites on actin and no cross-bridges will form.
D)A single twitch in skeletal muscle but no sustained contraction.
E)Contraction will occur,but the muscle will be stuck in the contracted state and unable to relax.

Question

In a laboratory experiment you have treated a muscle cell with a calcium channel blocker.The membrane still depolarizes,but the concentration of calcium never increases in the cytosol.Which of the following describes what will happen next?
A)Only one cross-bridge cycle will occur but no second cycle. 
B)Binding of myosin to actin will take place.
C)Tropomyosin will continue to cover the myosin binding sites on actin and no cross-bridges will form.
D)A single twitch in skeletal muscle but no sustained contraction.
E)Contraction will occur,but the muscle will be stuck in the contracted state and unable to relax.

Quizplus · Accepted Answer

The calcium channel blocker prevents the entry of calcium ions into the cytosol, which is required for the activation of the contractile proteins. Without calcium, the muscle cannot contract, and the myosin binding sites on actin will remain covered by tropomyosin, preventing the formation of cross-bridges. Therefore, choice C is the correct answer.

In a Laboratory Experiment You Have Treated a Muscle Cell