Describe the molecular activity that leads to muscle contractions, beginning at the neuromuscular junction

What will be an ideal response?


ANSWER: An action potential arriving at the neuromuscular junction results in a release of
acetylcholine, which triggers an action potential in the muscle fiber. This action potential
leads to an increase in the concentration of Ca2+ in the fiber’s cytosol, which triggers the
crossbridge cycle. The Ca2+ combines with troponin, inducing a conformation change that
moves tropomyosin away from the myosin-binding sites on thin filaments, Exposure of the
sites allows myosin crossbridges to bind and initiate the crossbridge cycle in which myosin
heads of thick filaments attach to a thin filament, pull, and release in cyclic reactions
powered by ATP hydrolysis.

Biology & Microbiology

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Why are leukocytes so central to second-line molecular defenses?

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