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Questions and Answers
What is the main function of the globular 'head' region of the myosin molecule?
What is the result of the hydrolysis of bound ATP in the myosin molecule?
What is the purpose of the repeated cycles of binding and release in muscle contraction?
According to the sliding-filament model, what is the mechanism of muscle contraction?
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What is the role of the 'tail' region of the myosin molecule?
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What is the net result of the cycles of change in the myosin molecule during muscle contraction?
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Study Notes
- A contracting muscle shortens, but the filaments that bring about contraction stay the same length.
- The filaments in a sarcomere slide past each other, similar to the segments of a telescoping support pole, to bring about contraction.
- The sliding-filament model explains muscle contraction, where thin and thick filaments ratchet past each other powered by myosin molecules.
- Myosin molecules have a long "tail" region that binds to the tails of other myosin molecules, forming the thick filament, and a globular "head" region that binds ATP.
- The hydrolysis of bound ATP converts myosin to a high-energy form that binds to actin, forming a cross-bridge between the myosin and the thin filament.
- The myosin head returns to its low-energy form as it pulls the thin filament toward the center of the sarcomere, contributing to muscle contraction.
- Muscle contraction requires repeated cycles of binding and release of myosin heads to actin filaments.
- During each cycle, the myosin head is freed from a cross-bridge, cleaves the newly bound ATP, and binds again to actin, repeating the process.
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Description
Understand the mechanism of muscle contraction through the sliding filament model, where thin and thick filaments slide past each other, powered by myosin molecules. Learn how this process explains the apparent paradox of muscle contraction. Quiz yourself on the details of muscle physiology and the myosin molecule's role in contraction.
