Which of the following is true of troponin and tropomyosin?
Correct answer: B. Tropomyosin binds to actin and prevents the myosin head from binding to actin
- A. Troponin binds to myosin and tropomyosin binds to actin
- B. Tropomyosin binds to actin and prevents the myosin head from binding to actin
- C. Both options A and B are correct
- D. None of these options are correct
Explanation
Option A: Troponin does not bind to myosin thus this option is incorrect.Option B: In a relaxed muscle fibre, the binding sites for myosin cross-bridges on actin filaments are covered by tropomyosin. Troponin is a protein to which calcium ions bind during contraction. Tropomyosin binds to actin and prevents the myosin head from binding to actin hence this option is correct.Option C: Option A is incorrect thus this option can't be selected.Option D: Option B is correct hence this option is incorrect.
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About Support and Movement
Support and movement covers the axial and appendicular skeleton, bone structure, joints and the arrangement of skeletal muscles. Muscle contraction is explained through actin, myosin, sliding filaments, calcium ions and ATP, while arthritis is distinguished as a disorder of joints rather than a normal part of movement.
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