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Myosin contains two binding sites for what two molecules?
ATP (--> ADP+Pi) and actin
Explain how a skeletal muscle contracts and relaxes?
Contraction:Calcium ion (from sarcoplasmic reticulum) binds to troponin of actin filament.Re-orientation occurs in actin filament allowing it to bind to the myosin filament.Globular head of myosin filament binds to actin filament.Myosin filament splits an ATP molecule and as result it bends causing actin filament (attached to it) to slide over it. When the overlap of actin and myosin filament is maximum, filaments will occupy less space thus muscle is in contracted state.Relaxation:ATP binds to myosin filament and myosin returns to its original position (relaxed state).Sarcoplasmic reticulum re-accumulates the calsium ion by active transport. As the result actin filament is dettached from myosin filament.When the overlap of myofibrils is minimal, muscle will be in relaxed state.
What do muscle fibers need to reset the myosin heads?
ATP binds myosin, allowing it to release actin and be in the weak binding state (a lack of ATP makes this step impossible, resulting in the rigor state characteristic of rigor mortis). The myosin then hydrolyzes the ATP and uses the energy to move into the "cocked back" conformation.
What are the proteins are involved in muscle contraction?
Actin and myosin
What molecule has a binding site for myosin heads?
Actin is the molecule that has a binding site for myosin heads. This interaction is crucial for muscle contraction as myosin binds to actin and generates force to cause muscle movement.
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.
What causes cross bridge detachment?
Cross bridge detachment occurs when ATP binds to the myosin head, causing it to release from the actin filament. This process is necessary for the muscle to relax and reset for another contraction.
What is the next step in muscle contraction after the actin changes shape?
Actin Changes ShapeApexMyosin binds to ActinAPEX
What is the compound that binds myosin and provides energy for the power stroke?
Adenosine triphosphate (ATP) is the compound that binds to myosin and provides the energy needed for the power stroke in muscle contraction. Myosin hydrolyzes ATP to ADP and inorganic phosphate during the power stroke, releasing energy that enables the myosin head to move along the actin filament.
When calcium is released into the sarcomere it does what?
When calcium is released into the sarcomere, it binds to troponin, causing a conformational change that moves tropomyosin away from actin's myosin-binding sites. This exposure allows myosin heads to attach to actin filaments, initiating the cross-bridge cycle and leading to muscle contraction. The presence of calcium is essential for this process, as it effectively triggers the contraction mechanism in muscle fibers.
When a muscle cell responds to a stimulus calcium is released from the?
When a muscle cell responds to a stimulus, calcium is released from the sarcoplasmic reticulum. This calcium binds to troponin, triggering a conformational change that allows myosin to bind to actin and initiate muscle contraction.
What is the key intracellular event that stimulates muscle contraction?
The key intracellular event that stimulates muscle contraction is the release of calcium ions from the sarcoplasmic reticulum within muscle cells. This calcium binds to troponin, causing a conformational change that allows myosin heads to bind to actin filaments and initiate the sliding process that shortens the muscle fibers and results in muscle contraction.
