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.
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Pharmacogenetics is a new field of study that arose from the study of
A) cholesterol uptake. B) mixed-function oxidases. C) ATP-dependent calcium ATPases. D) phagocytosis by specifically vertebrate white blood cells. E) residual bodies.
Fungi parasitic on plants produce specialized hyphae, called ____, that penetrate the host
a. asci b. basidia
c. soredia d. haustoria e. secondary mycelia
What product that is required by plants do animals–as well as plants–produce during cellular respiration?
A) CO2 B) oxygen C) glucose D) ADP
Why are leukocytes so central to second-line molecular defenses?
A) Leukocytes trigger other cells of the immune system to produce second-line molecular defenses. B) Leukocytes remove second-line molecular defenses to inhibit damage to healthy tissues in the surrounding area. C) Leukocytes produce second-line molecular defenses. D) Leukocytes have nothing to do with second-line molecular defenses. E) Leukocytes respond to the production of second-line molecular defenses.