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What is the power source forsliding filament model of muscle movement?
Adenosine triphosphate. (ATP)
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 requires ATP to function?
Proteins that carry out active transport such as Na/K ion channels requires ATP. Also metabolic enzymes such as kinases which can phosphorylate its substrate also need ATP; For example hexokinase convert the glucose to glucose 6 phosphate in the first glycolysis step with the expense of an ATP molecule.The muscle protein myosin can use ATP to flex its head, pulling on the muscle protein actin, causing the actin filament to slide past the myosin filament producing contraction of the muscle. Sometimes myosin does this with just ion transfers without requiring ATP, but the reaction using ATP is more dependable.
What is an explanation of how a muscle contracts?
The popular model of muscle contraction is "Sliding filament hypothesis" which is proposed by A.F.Huxely and H.E. Huxely. According to this hypothesis filaments of myofibrils (actin and myosin) slide over each other for the contraction. Muscle cells are not compressed or stretched. Calcium ions are released from sarcoplasmic reticulum causing re-orientation in actin filament. This enables it to bind to the myosin extensions (known as globular heads or cross bridges). The myosin filament binds and splits an ATP molecule. As the result the myosin head binds to the actin filament further ahead. The globular head moves (bends) and the actin filament attached to it also moves and overlaps the myosin filament. Because of this the actin and myosin filament occupy less space when their overlap is maximum. At this stage the sarcomere (containing unit of myofibrils) is contracted thus the muscle contraction occurs. As long as the sarcoplasmic reticulum provides the ATP and calsium ions, the myosin can crawl along the actin and muscle contractions continue. The enzyme ATPase breaks down ATP into ADP to provide energy for muscle contraction. The energy is stored in form of glycogen in muscles which is converted into glucose and then into ATP when muscles contract. During intensive muscle activity phosphocreatin is broken down into creatin and phosphate group. This phosphate group then combines with ADP to form ATP. animation will help you in understanding muscle contraction. see the related link below
What molecule directly supplies energy to myosin to allow the filaments to contract?
Adenosine triphosphate (ATP) is the molecule that directly supplies energy to myosin during muscle contraction. Myosin uses ATP to power the movement of actin filaments, leading to muscle contraction.
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 concept used to explain the action of filaments in muscle contraction?
Actin is the thin filament and contains troposin and tropomyosin. Myosin is the thick filament and contains the myosin heads that will later hydrolyze ATP and essentially "walk" up and down the actin filament thus shortening the sarcomere. Once calcium binds to troposin, tropomyosin will be moved away from the active myosin actin binding site and ATP hydrolysis can begin.
Does muscle relaxation does not require ATP?
Both muscle relaxation and muscle contraction require ATP.
What filament is responsible for the pulling and what filament is pulled in the sliding filament theory?
In the sliding filament theory of muscle contraction, the thin filament (actin) slides over the thick filament (myosin). Myosin is responsible for pulling the actin filaments towards the center of the sarcomere during muscle contraction.
What happens when ATP supplies energy for thin filaments in a muscle fiber to slide over the thick filaments?
When ATP supplies energy for thin filaments to slide over thick filaments in a muscle fiber, it triggers the contraction process known as the sliding filament theory. ATP binds to myosin heads on the thick filaments, causing them to detach from the actin sites on the thin filaments. Hydrolysis of ATP then re-cocks the myosin heads, allowing them to bind to new sites on the actin filaments. This cycle repeats, resulting in the shortening of the muscle fiber and overall muscle contraction.
What protein is not in thin filament?
Myosin is a protein that is not found in the thin filament. Myosin is a motor protein that is primarily found in the thick filament of muscle cells and is responsible for muscle contraction. The thin filament contains proteins such as actin, tropomyosin, and troponin.
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.
