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Where does ATP attach during muscle contraction?
During muscle contraction, ATP attaches to the myosin heads of the thick filaments in the muscle fibers. When ATP binds to myosin, it causes the myosin head to detach from the actin filament, allowing for a new cycle of cross-bridge formation and muscle contraction to occur. The hydrolysis of ATP then provides the energy necessary for the myosin head to pivot and pull the actin filament, leading to muscle shortening.
What is the tough translucent sheath that surrounds the skeletal muscle and binds it together is what?
The tough translucent sheath that surrounds skeletal muscle and binds it together is called the epimysium. This connective tissue layer encases the entire muscle, providing protection and structural support. It also helps in the transmission of force generated by the muscle fibers to the tendons and bones. The epimysium is continuous with other connective tissue layers, such as perimysium and endomysium, which further organize and support the muscle fibers within.
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 role of tropomyosin in skeletal muscle?
Tropomyosin is a regulatory protein in skeletal muscle that plays a critical role in muscle contraction. It binds to actin filaments and, in the absence of calcium ions, blocks the binding sites for myosin, preventing muscle contraction. When calcium ions are released during muscle activation, they bind to troponin, causing a conformational change that moves tropomyosin away from the binding sites, allowing myosin to interact with actin and initiate contraction. Thus, tropomyosin is essential for the regulation of muscle contraction and relaxation.
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.
The active site involved in cross-bridge formation?
The active site involved in cross-bridge formation is located on the myosin protein of thick filaments in muscle fibers. This site binds to specific sites on the actin filaments of thin filaments, facilitating the interaction necessary for muscle contraction. The binding of myosin to actin is regulated by the presence of calcium ions and ATP, which enable the myosin heads to attach, pivot, and pull the actin filaments, resulting in muscle shortening. This process is a key component of the sliding filament theory of muscle contraction.
What is the next step in muscle contraction after the actin changes shape?
Actin Changes ShapeApexMyosin binds to ActinAPEX
