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What function do calcium ions perform during the contraction of skeletal muscle?

Answer 1

Expose myosin-binding sites on actin filament by displacing the tropomyosin present on actin filament.

Calcium ions released by the sarcoplasmic reticulum play a vital role in contraction of muscles. From sarcoplasmic reticulum these ions#(Ca^(2+))# released into the cytoplasm of the muscle cell, specifically called as sarcoplasm.

In sarcoplasm, #Ca^(2+)# ions attach to one of the three molecules of troponin. This causes the tropomyosin to displace slightly from the actin filaments. This displacement expose the binding sites on the actin filament. Thus myosin heads get instantly attached to the binding sites on actin filament and contraction of muscles occurs.

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Answer 2

Sophia Atencio

By binding to the protein complex troponin, calcium ions play a critical role during skeletal muscle contraction. This process causes a conformational change in the protein tropomyosin, exposing the myosin-binding sites on the actin filaments and facilitating the binding and contraction process of the myosin heads.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.