What does troponin bind to, and what happens when it binds?Multiple ChoiceCa2+; tropomyosin shiftstropomyosin; the sarcomere relaxesacetylcholine; the sarcomere shortensATP; tropomyosin returns to normal positionT tubules; the sarcomere shortens
Question
What does troponin bind to, and what happens when it binds?Multiple ChoiceCa2+; tropomyosin shiftstropomyosin; the sarcomere relaxesacetylcholine; the sarcomere shortensATP; tropomyosin returns to normal positionT tubules; the sarcomere shortens
Solution
The correct answer is "Ca2+; tropomyosin shifts".
Here's the step by step explanation:
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Troponin is a complex of three proteins that is integral to muscle contraction in skeletal and cardiac muscle, but not smooth muscle.
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It is attached to the protein tropomyosin and lies within the groove between actin filaments in muscle tissue.
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In a relaxed muscle, tropomyosin blocks the attachment sites for the myosin crossbridges (heads), preventing contraction.
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When the muscle cell is stimulated to contract by an action potential, calcium channels open in the sarcoplasmic reticulum and release calcium into the cytoplasm.
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Calcium ions bind to the troponin complex, causing a conformational change in the complex.
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This conformational change shifts tropomyosin out of the way, exposing the myosin-binding sites on actin and allowing muscle contraction to proceed.
So, in summary, troponin binds to calcium ions, and when it does, it causes tropomyosin to shift, exposing the myosin-binding sites on actin and allowing muscle contraction to proceed.
Similar Questions
Describe what must occur before tropomyosin can move away from the myosin binding sites.Multiple choice question.The sarcomere has to shortenActin and elastic fibers have to recoilCalcium must bind to troponinATP has to bind to tropomyosin
Uncovering binding sites for myosin on actin myofilaments involves troponin binding to ____________.Multiple ChoiceT tubulestropomyosinphosphatecalcium ions
When calcium ion binds to troponinQuestion 9Select one:a.active sites on the myosin are exposed.b.muscle relaxation occurs.c.myosin shortens.d.tropomyosin moves into the groove between the helical actin strands.e.actin heads will bind to myosin.
During contraction of a muscle, calcium ions bind to ______ which moves _______ out of the way. This now uncovers binding sites on the __________ myofilament. multiple choice 1troponin; tropomyosin; myosintroponin; tropomyosin; actintropomyosin; troponin; myosintropomyosin; troponin; actin 2. What molecules are attached to the myosin head from the previous cycle of movement? multiple choice 2ATP and phosphateADP and phosphateATP and calcium ionsADP and calcium ions 3. What is released in the process of cross-bridge formation? multiple choice 3ADPPhosphateATPCalcium ions 4. When the myosin head is moved, what is released (from the myosin head)? multiple choice 4ATPADPPhosphateCalcium ions 5. After the myosin head returns to its upright position, what occurs if calcium ions are still present? multiple choice 5Actin myofilaments move away from the M line.The entire sequence is repeated.Troponin blocks the binding sites on actin.Myosin heads will no longer bind to actin.
n order for muscle contraction to occur during exercise calcium must bind to which of the following proteins? troponin. tropomyosin. myosin. actin.
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