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Which event causes cross bridge detachment?
The binding of ATP to the myosin head causes cross bridge detachment by disrupting the binding between myosin and actin. ATP provides the energy necessary for myosin to release from actin and reset for the next contraction cycle.
What protein shields the myosin-binding site preventing contraction from happening at rest?
ATP entering myosin head
What converts the myosin head into the high-energy state?
The hydrolysis of ATP by myosin activates the myosin head and converts it into a high-energy state. This process releases energy that is used to power muscle contraction.
Myosin contains two binding sites for what two molecules?
ATP (--> ADP+Pi) and actin
When does the myosin head cock back to store energy for the next cycle?
The myosin head cocks back to store energy for the next cycle during the cross-bridge cycling process in muscle contraction. This occurs after the powerstroke phase, where the myosin head binds to actin and pulls the thin filament towards the center of the sarcomere. The cocking of the myosin head allows it to reset and be ready for the next binding to actin during muscle contraction.
What is the role of tropomyosin in muscles?
Tropomyosin regulates muscle contraction by blocking myosin binding sites on actin, preventing cross-bridge formation. When calcium binds to troponin, tropomyosin shifts, exposing the binding sites and allowing for cross-bridge formation, leading to muscle contraction.
What is the role is tropomyosin muscle?
Short answer: Tropomyosin wraps around an actin filament to form a functional actin filament or aka. thin filament. It's purpose is involved in the powerstroke of the myosin head. It does this by kind of like a hook. If you have a hook and you grab a long rope and pull it towards you, the hook is a thick filament (myosin) and the rope is a thin filament (actin). Troppmyosin will block the hook from latching onto the rope in normal resting phase. When it is released (by calcium), you can now freely hook the rope and pull it towards you.Long answer:Tropomyosin wrap around actin like a slinky. It functions to block myosin from attaching to actin. This is done by troponin complex (TN-I, TN-C, TN-T). In the sliding filament model you have the thick (myosin) and thin (actin) filaments sliding past one another. This sliding action is performed by crossbridges formed between the myosin head and myosin-binding site on the actin.Normally in resting phase, when the muscle is relaxed, the troponin complex is blocking the myosin-binding site. This prevents the myosin head from attaching to the myosin-binding site. In addition it is preventing a protein on the myosin head (myosin ATPase) from hydrolizing an ATP for what it will later use in a powerstroke. Whenever the myosin-binding site becomes available, it will always want to attach to the myosin head. This is the high affinity it has. The myosin-binding site reveals itself when calcium enters and makes a conformational change on that troponin complex (first paragraph). Actually it adheres to TN-C specifically (TN-C = troponin calcium). So when calcium attaches to troponin complex it reveals the myosin-binding site. As the myosin-binding site is revealed the head is now free to attach and the myosin ATPase is now free to hydrolyze ATP. It takes that energy to bend the myosin head 45 degrees and it attaches to the myosin-binding site. SUCCESS!However, that's only half the story because now you need detach. Another ATP molecule comes in and it detaches the myosin head from the thin filament (specifically myosin-binding site). It's important to note here that the ATP is not hydrolyzed and it's only used to restore the resting phase. Calcium is taken back by pumps, the troponin complex rears it's ugly face and the myosin head is blocked once again.When a person dies and no longer produces ATP, the muscles that were contracted cannot release because new ATP doesn't exist to restore the resting phase. This is rigor mortis.
Which step allows actin and myosin to release from each other?
an ATP molecule attaches to myosin apex answers
What is needed to attach and detach myosin heads from actin?
For attachment of myosin heads to actin, calcium ions must bind to troponin, causing tropomyosin to move out of the way, exposing the binding site on actin. ATP then binds to the myosin head, leading to its activation and attachment to actin. For detachment, ATP is hydrolyzed, causing a conformational change in the myosin head that releases it from actin.
What substances causes the myosin head to change shape?
ATP (adenosine triphosphate) is the main substance that causes the myosin head to change shape during muscle contraction. When ATP binds to the myosin head, it energizes the myosin molecule and allows it to detach from actin, resetting the myosin head for the next contraction cycle.
What happens to ATP when it binds to Myosin?
When ATP binds to myosin, it causes myosin to release actin, allowing for muscle relaxation. The energy stored in ATP is used to detach myosin from actin and prepare the cross-bridge for another contraction cycle.
Describe the process that cause the muscle to contract?
# When the muscle is in a resting state, thin strands of a protein called tropomyosin are wrapped around the actin filaments, blocking the myosin binding sites. This keeps the myosin from binding to actin. # Molecules called troponin are attached to the tropomyosin. # When calcium is introduced into the muscle cell, calcium ions bind to troponin molecules. # Calcium then pulls troponin, causing tropomyosin to be moved as well, therefore causing the myosin binding sites on the actin to be exposed. # Myosin binds to the now-exposed binding sites. # As soon as the myosin head binds to actin, the head bends at its hinge. # Once the head bends, the myosin loses energy, and remains attached to the actin. # When re-energized by adenosine triphosphate (ATP), the myosin head detaches from the actin filament, and is ready to attach and bend again. # The collective bending of numerous myosin heads (all in the same direction), combine to move the actin molecules closer together. This results in a muscle contraction.
