Icholine binds to a GPCR on heart muscle, making the stimulates a G protein, whi
ID: 255830 • Letter: I
Question
Icholine binds to a GPCR on heart muscle, making the stimulates a G protein, which opens a K+ channel in the heart beat more slowly. The activated plasma membrane, as shown in the below. Which of the following would decrease this effect of the acetylcholine dosed K-channel EXTRACELLULAR SPACE 1 G PROTEIN G proteln A) addition of a high concentration of GTP 8) addition of a drug that promotes the a subunit to exchange GDP for GTP C) addition of a drug that reduces the a subunit to exchange GDP for GTP D) mutations in the acetylcholine receptor that increase its interaction with the G protein 42. Which of the following statements is true? A) MAP kinase is important for phosphorylating MAP kinase kinase. B) Pl 3-kinase phosphorylates PIP2 to generate PIP3 in the plasma membrane to promote cell survival. C) Ras becomes activated when an RTK directly promotes Ras to exchange its bound GDP for GTFP D) STAT proteins phosphorylate JAK proteins, which then enter the nucleus and activate gene transcription. 43. Adenylyl cyclase stimulation takes place after receptors bind hormone because A) of the generation of GTP-bound a subunit of G protein. B) of the generation of GDP-bound a subunit of G protein. C) adenylyl cyclase binds to receptor D) the G protein subunit converts ATP to cAMP 44. Activation of skeletal muscle phosphorylase kinase is most likely due to A) parathyroid hormone receptor activation, which results in increased levels of calcium in the blood. B) insulin receptor activation, which results in increased levels of sugar in the blood. C) adrenaline binding of cell receptors, leading to increased blood levels of glucose. D) glucocortioid binding of cell receptors, leading to decreased blood levels of glucose. 45. Increased production of IP3 in muscle cells of the gastrointestinal tract can leads to A) excess levels of cAMP B) inactivation of thick filament ATPase subunits C) increased levels of calcium within the cytosol of smooth muscle cells D) increased levels of calmodulin within the cytosol of smooth muscle cellsExplanation / Answer
Answer 41:
The correct option will be (B) The addition of a drug that promotes the alpha subunit to exchange GDP for GTP.
This is because, while the alpha sub unit of G-protein is linked to GTP, it is activated and will carry out the function of acetylcholine and thus the effect will increase. But so as to decrease the effect, the alpha subunit of G-protein has to be inactive. When a alpha subunit is linked to GDP rather than GTP, it is inactive state.
Answer 42:
The correct statement is (B). since it is true
PI-3 kinase phosphorylates the PIP2 in the plasma membrane to produce PIP3 which stimulates a protein serine/threionine kinase AKT which directly promotes cell survival and proliferation.
Answer 43:
Correct option will be (A).
Hormone stimulates a G-protein linked receptor which activates the alpha subunit of G-protein which means binding of GTP to it. This stimulated subunit activates the adenylyl cyclase which converts ATP to cAMP.
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