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ATP (--> ADP+Pi) and actin
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Do the heads of myosin molecules contact the actin filaments when a muscle is relaxed?
No, the heads of myosin molecules do not contact the actin filaments when a muscle is relaxed. In a relaxed state, the binding sites on actin are blocked by tropomyosin, preventing myosin heads from attaching. When calcium ions are released during muscle contraction, they bind to troponin, causing a conformational change that moves tropomyosin and exposes the binding sites for myosin, allowing contraction to occur.
Does Tropomyosin molecules move and expose specific sites on myosin filaments?
Yes, tropomyosin molecules block specific binding sites on actin filaments in relaxed muscle. When calcium ions bind to troponin, it causes a conformational change in tropomyosin, exposing the binding sites on actin, which allows myosin heads to bind and initiate muscle contraction.
The binding of calcium to which molecule causes the myosin binding sites to be exposed?
Troponin binds to the Calcium ions to expose the actin to the myosin heads.
What does binding of the myosin heads sequentially prevent?
Binding of the myosin heads sequentially prevents the actin-binding sites on the thin filaments from becoming continuously occupied by myosin heads, allowing for the muscle fiber to relax and the sarcomere to lengthen.
Binding sites on the actin molecules are covered by troponin and?
tropomyosin in resting muscles. When calcium binds to troponin, it causes tropomyosin to move, exposing the binding sites on actin. This allows myosin heads to bind to actin, leading to muscle contraction.
What is the role of the skeletal muscles?
Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.
Do the heads of myosin molecules contact the actin filaments when a muscle is relaxed?
No, the heads of myosin molecules do not contact the actin filaments when a muscle is relaxed. In a relaxed state, the binding sites on actin are blocked by tropomyosin, preventing myosin heads from attaching. When calcium ions are released during muscle contraction, they bind to troponin, causing a conformational change that moves tropomyosin and exposes the binding sites for myosin, allowing contraction to occur.
Does Tropomyosin molecules move and expose specific sites on myosin filaments?
Yes, tropomyosin molecules block specific binding sites on actin filaments in relaxed muscle. When calcium ions bind to troponin, it causes a conformational change in tropomyosin, exposing the binding sites on actin, which allows myosin heads to bind and initiate muscle contraction.
ADP molecules on the surface of actin serve as active sites for the formation of cross bridges with molecules of?
ATP not ADP binds to actin-myosin and is cleaved by to ADP.
What blocks the myosin binding sites on the actin molecule preventing cross bridge formation?
The tropomyosin molecule blocks the active sites of the actin. Troponin is a molecule that is bound to the tropomyosin. Troponin needs CA+ (calcium ions) to bind to it in order to rotate the tropomyosin molecule and expose the actin molecules for the myosin heads to interact for muscle contraction.
The binding of calcium to which molecule causes the myosin binding sites to be exposed?
Troponin binds to the Calcium ions to expose the actin to the myosin heads.
The ability of myosin to interact with actin is regulated by the binding of?
The ability of myosin to interact with actin is regulated by the binding of calcium ions to troponin, which then allows tropomyosin to move away from the binding site on actin. This exposes the myosin-binding sites on actin, allowing myosin to bind and initiate muscle contraction.
What does binding of the myosin heads sequentially prevent?
Binding of the myosin heads sequentially prevents the actin-binding sites on the thin filaments from becoming continuously occupied by myosin heads, allowing for the muscle fiber to relax and the sarcomere to lengthen.
What myofilaments contains troponin and tropomyosin?
The thin filament in skeletal muscle contains troponin and tropomyosin. Troponin regulates the interaction between actin and myosin during muscle contraction, while tropomyosin helps to block the myosin-binding sites on actin when the muscle is at rest.
What muscle cell protein covers the myosin binding sites on actin fimlaments?
tropomyosin
Which myofilament has a binding site for myosin head?
The myofilament that has a binding site for the myosin head is actin. Actin filaments contain specific regions known as binding sites that interact with the myosin heads during muscle contraction. This interaction is crucial for the sliding filament theory, where the myosin heads pull the actin filaments to shorten the muscle fiber. The binding of myosin to actin is regulated by the presence of calcium ions and the protein tropomyosin.
When the sarcomere is at rest what is covering the active sites on actin?
When the sarcomere is at rest, the active sites on actin are covered by tropomyosin molecules. Tropomyosin blocks the myosin-binding sites on actin, preventing cross-bridge formation and muscle contraction.
