Question

A student simulates muscle contraction in a model using the following order of events:

Calcium pumps of the sarcoplasmic reticulum open.
Tropomyosin moves.
Calcium ions bind to troponin.
Myosin heads bend to attach to actin filaments.

Based on the order of steps in the student's model, will the muscle successfully contract?
Yes, the muscle model will successfully contract because the sequence is correct No, because the calcium pumps cannot open before the tropomyosin moves
No, because tropomyosin cannot move before the myosin heads attach to actin
No, because tropomyosin cannot move before calcium ions bind to troponin

Answer 1

No, because tropomyosin cannot move before calcium ions bind to troponin

Step-by-step explanation:

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Answer 2

No, because tropomyosin cannot move before calcium ions bind to troponin

Step-by-step explanation:

Tropomyosin cannot move unless calcium binds to troponin. This is because this is the main purpose of calcium being in this system. Tropomyosin acts as a gateway and stops actin to bind with myosin. If tropomyosin moves anyways, then there is no requirement of calcium in the system. It is of further importance to consider that stimulus from nerve impulse causes calcium gates to open, thus causing series of actions causing muscle contraction.