A) calcium release by the ER.
B) nitric oxide.
C) guanylyl cyclase.
D) calmodulin.
E) all of the above
3) All of the following are second messengers except
A) calcium ions.
B) IP3.
C) DAG.
D) cameleons.
E) PDGF.
5) Hydrophobic messengers include which of the following?
A) retinoids
B) cAMP
C) pertussis toxin
D) calcium ions
E) ryanodine
7) Which of the following would be characterized as a juxtacrine signal?
A) contact-dependent
B) endocrine
C) self-responding
D) distal neighbors
E) both choices B and D
9) Which of the following ligands would not have an intracellular receptor?
A) cortisol
B) retinoic acid
C) thyroxine
D) epinephrine
E) progesterone
Base your answers to the questions below on the following information:
You have isolated a factor from the blood of a space alien and named it XFF (for X-files factor). Based on preliminary data, you think that XFF could be one of three compounds normally found in human blood: epidermal growth factor (EGF), epinephrine, or estrogen.
11) You obtain two different preparations of XFF, one of which contains the receptors for XFF. You perform a binding assay and obtain a standard curve. Based upon this data, what value would reflect the affinity of the receptor for the ligand? (Assume a 1 XFF-to-1 receptor interaction.)
A) Kd
B) Bmax
C) Kd - Bmax
D)
E) The affinity cannot be detertmined from the information available
13) You add a large amount of XFF to cultured liver cells. Which of the following might you observe if XFF can bind to human epinephrine receptors?
A) increased cell division
B) decreased protein synthesis
C) glycogen breakdown
D) glucose-6-phosphate polymerization
E) all of the above
15) After determining which preparation contained the XFF receptor, you wish to determine the properties of the ligand receptor. Using a radioactive XFF, you wish to determine if the properties are similar to that of epinephrine and the epinephrine receptor. If so, you expect to find the radioactive XFF
A) within the cell.
B) associated with the ER.
C) on the cell surface.
D) associated with mitochondria.
E) in the nucleus.
17) Which of the following pairings is not correct?
A) adenylyl cyclase-ATP
B) phospholipase C-diacylglycerol (DAG)
C) phospholipase C-inositol triphosphate
D) calmodulin-calcium ions
19) G protein-adenyl cyclase activity has been shown, in some cases, to be associated with certain diseases. In the case of cholera, which of the following is not correct?
A) Vibrio cholera bacteria colonize the gut.
B) Cholera toxin is secreted by Vibrio cholera bacteria.
C) The cholera toxin causes the cells of the gut to take in salts and fluids.
D) Cholera toxin alters Gs so that it no longer hydrolyzes GTP.
E) The toxin, by altering Gs, keeps intracellular cAMP levels high and doesn't allow them to decrease.
21) You are testing a drug that might be marketed as an anti-inflammatory agent. It would be a good choice if it possessed which of the following responses?
A) stimulates the release of prostaglandins
B) blocks adenylate cyclase activity
C) blocks an enzyme associated with arachidonic acid production
D) stimulates the activation of platelets
E) all of the above
23) Kinases and phosphatases are essential in the cell because they
A) help turn proteins "on and off" through changes in phosphorylation status.
B) are enzymes that destroy damaged proteins.
C) sense short poly-A tails in mRNA as a signal to degrade the mRNA.
D) destroy second messengers, thereby turning off a signal transduction pathway.
E) all of the above
25) A developing organism's failure to produce muscle tissue is most likely due to
A) underdevelopment of the ectoderm.
B) underdevelopment of the endoderm.
C) fibroblast growth factor receptor mutations.
D) adenylate cyclase mutations.
E) missing chromosomes.
27) Prostaglandins are not
A) endocrine hormones.
B) important in smooth muscle function.
C) paracrine hormones.
D) stimulators of inflammation.
E) formed from arachidonic acid.
29) You have recently identified a molecule that you believe to be a ligand associated with a signal transduction mechanism. All you know about this ligand is that chemically it is hydrophilic. As a result, you expect it to interact with its receptor
A) at the outer cell surface.
B) within the cytoplasm of the cell.
C) within the nucleus of the cell.
D) on the cytoplasmic side of the plasma membrane.
E) all of the above
31) You wish to determine if cytosolic calcium fluxes are associated with signal transduction in a particular cell type. One means of observing the calcium fluxes would be to utilize
A) caspases.
B) cytochrome c.
C) nitric oxide.
D) radioactive cAMP.
E) cameleons.
33) IP3 receptors are associated with
A) plasma membranes.
B) intracellular membranes.
C) mitochondrial membranes.
D) ER membranes.
E) lysosomes.
35) Kinases are enzymes that
A) add phosphate groups.
B) do not alter target activity.
C) are always inhibitory.
D) remove phosphate groups.
E) all of the above
37) MAPKs are activated by
A) methylation.
B) microtubules.
C) membranes.
D) mitogens.
E) methionine.
39) All of the following are second messengers, except
A) cyclic adenosine monophosphate.
B) inositol trisphosphate.
C) diacylglycerol.
D) epinephrine.
E) calcium ions.
E) Ras activates a cascade of phosphorylation events.
41) Killer lymphocytes can elicit self-destruct mechanisms in target cells by interacting with
A) Fas ligand.
B) Fas receptors.
C) Ras ligand.
D) adaptor proteins.
E) procaspase.
43) Mice lacking the ability to make caspase-9 die as the result of numerous defects. During the necropsy (animal autopsy) of the animal you note that the brains of these mice are
A) unregulated growth of the nerve cells.
B) lack of apoptosis of some cells.
C) overstimulation of G-protein-mediated transduction.
D) overproduction of the Etr1 receptor protein.
E) all of the above
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