Match each perturbation of the skeletal muscle contraction cycle with the conseq
ID: 3477537 • Letter: M
Question
Match each perturbation of the skeletal muscle contraction cycle with the consequences it would cause. Each answer can be used only once.
Remove all ATP from the muscle fiber.
Mutate mysoin so that it would not be able to hydrolyze ATP and produce Pi or ADP
Deplete muscle cells of intracellular calcium
Actin would remain bound to myosin, the rigor state would be maintained.
Myosin would be able to release actin, but would not be able to rebind to actin to create a weak cross-bridge
tropomyosin would block actin-myosin binding site, power stroke would not occur
-Remove all ATP from the muscle fiber.
-Mutate mysoin so that it would not be able to hydrolyze ATP and produce Pi or ADP
-Deplete muscle cells of intracellular calcium
A.Actin would remain bound to myosin, the rigor state would be maintained.
B.Myosin would be able to release actin, but would not be able to rebind to actin to create a weak cross-bridge
C.tropomyosin would block actin-myosin binding site, power stroke would not occur
Explanation / Answer
1. Removal of all ATPs from muscle fibre cause actin remain bound with myosin and rigor
state would be maintained because, in contraction cycle muscle one part of myosin
head attaches to the binding site on the actin but the head has another binding site for
ATP. ATP binding causes the myosin head to detach from actin filament, so in absent
of ATP myosin head remain attached with actin.
2. If ATP is not hydrolyse into ADP and Pi (inorganic phosphate), myosin would be able to
release actin but it not able to rebind actin to create cross bridge because cross bridge
formation occurs when myosin head attaches to the actin while ADP and Pi are still
bound to myosin.
3. When intracellular Ca++ deplete in muscle cell, tropomyosin would block actin-myosin
binding site & power stroke would not occure because as long as Ca++ remain in the
sarcoplasm to bind to troponin which keeps the actin binding sites unshielded or
uncover.Troponin and tropomyosin form a complex (troponin-tropomyosin complex)
that prevents myosin head from binding with sites on actin filaments.