Are the following statements true or false? 1. For a striated muscle to contract

Question

Are the following statements true or false?

1. For a striated muscle to contract, sarcomere tropomyosin must bind calcium so that the adjacent troponin moves and permits myosin to bind to actin.

2. Under resting conditions, the muscle cell cytoplasmic calcium is maintained at about 10-2 molar.

3. Microfilaments are polar macromolecules assemblies of tubulin.

4. Actin-based microfilaments are present in plant cells.

5. Activation energy acts as a barrier preventing thermodynamically unstable reactants from reaching equilibrium.

6. Phosphoglycerides include cholesterol, phosphatidylcholine, and phosphatidylethanolamine among other.

Explanation / Answer

1. True. Generally tropomyosin binds to the myosin binding sites of the actin. Troponin gets activated by calcium and then regulates tropomyosin and change its conformation which in turn make the actin binding site available for the myosin to bind which is important for the process of muscle contraction to occur.

2. False. Calcium concentration is very less in the cell in testing conditions. Even in excited state it is 400 nM.

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