Deck 14: Signal Transduction Mechanisms: Ii Messengers and Receptors

Question 1

Blood pressure is regulated by the second messenger

A)Ca2+.
B)CO.
C)IP3.
D)NO.
E)cAMP.

Answer 1

D

Question 2

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 dramatically enlarged. This is most likely a result of

A)overstimulation of G- protein mediated transduction.
B)overproduction of the Etr1 receptor protein.
C)lack of apoptosis of some cells.
D)unregulated growth of the nerve cells.
E)all of the above

Answer 2

C

Question 3

It would then be useful to determine if the mechanism of action for the XFF - XFF receptor is similar to that of estrogen or epinephrine. To test this, you use a nonhydrolyzable analog of GTP in the reaction mixture. If the mechanism is still similar to that of epinephrine, you would expect the cellular responses would be

A)delayed.
B)blocked.
C)prolonged.
D)both B and C
E)You cannot determine this from the given information.

Answer 3

C

Question 4

Kinases and phosphatases are essential in the cell because they

A)sense short poly A tails in mRNA as a signal to degrade the mRNA.
B)are enzymes that destroy damaged proteins.
C)help turn proteins "on and off" through changes in phosphorylation status.
D)destroy second messengers, thereby turning off a signal transduction pathway.
E)all of the above

Question 5

Which of the following is NOT a receptor tyrosine kinase?

A)EGF
B)TGF
C)FGF
D)TGF
E)PDGF

Question 6

Phosphatases are enzymes that

A)are always inhibitory.
B)remove phosphate groups.
C)add phosphate groups.
D)do not alter target activity.
E)all of the above

Question 7

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.
You argue with one of your fellow students that other features of the protein suggest that the protein is much like EGF. To discredit this, you would show the data obtained with

A)amino acid phosphorylation.
B)tyrosine kinase inhibition studies.
C)radioactive XFF.
D)binding assay.
E)use of nonhydrolyzable GTP analogs.

Question 8

IP3 receptors are associated with

A)lysosome.
B)ER membranes.
C)mitochondrial membranes.
D)intracellular membranes.
E)plasma membranes.

Question 9

Which of the following statements concerning the properties of ligands for intracellular receptor systems is correct?

A)Some ligands are carried in the blood bound to specific proteins.
B)Steroids are produced from cholesterol.
C)Changes in the composition of your diet can affect the concentration of some of these ligands in your body.
D)both A and C
E)choices A, B, and C

Question 10

To have a hormone receptor system that is responsive to changes in hormone concentration, it is useful if the concentration of the hormone is

A)never more than 10 times the Kd.
B)far below the Kd before the stimulation of hormone secretion.
C)always more than 10 times the Kd.
D)far above the Kd before the stimulation of hormone secretion.
E)always constant.

Question 11

Prostaglandins are NOT

A)important in smooth muscle function.
B)endocrine hormones.
C)stimulators of inflammation.
D)formed from arachidonic acid.
E)paracrine hormones.

Question 12

All of the following participate in apoptosis EXCEPT

A)death promoting proteins.
B)calcium ions.
C)Bcl- 2.
D)caspases.
E)mitochondria.

Question 13

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)stimulates the activation of platelets
C)blocks adenylate cyclase activity
D)blocks an enzyme associated with arachidonic acid production
E)all of the above

Question 14

Desensitization of a cell to a ligand may involve all BUT

A)a lessened response to the ligand.
B)receptor down- regulation.
C)lowered affinity of a receptor for the ligand.
D)destruction of the ligand.
E)receptor- mediated endocytosis.

Question 15

When nitric oxide is used in the dilation of smooth muscle cells, which of the following would interfere with the relaxation of the smooth muscle cells? Inhibitors of

A)nitric oxide.
B)calmodulin.
C)calcium release by the ER.
D)guanylyl cyclase.
E)all of the above

Question 16

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)cameleons.
B)caspases.
C)nitric oxide.
D)radioactive cAMP.
E)cytochrome c.

Question 17

Kinases are enzymes that

A)remove phosphate groups.
B)add phosphate groups.
C)do not alter target activity.
D)are always inhibitory.
E)all of the above.

Question 18

With regard to hormones, responses occurring over the shortest distance would be classified as

A)exocrine.
B)paracrine.
C)endocrine.
D)Choices A, B, and C all act over the same distance.
E)none of the above

Question 19

All of the following are second messengers, EXCEPT

A)epinephrine.
B)calcium ions.
C)diacylglycerol.
D)inositol trisphosphate.
E)cyclic adenosine monophosphate.

Question 20

MAPKs are activated by

A)microtubules.
B)methylation.
C)membranes.
D)mitogens.
E)methionine.

Question 21

Design experiments that would allow you to independently detect each of the following: G- protein mediated signal transduction, nitric oxide signal transduction, and calcium ion fluxes.

Question 22

In ulcerative colitis, gas within the lumen of the large intestine can have as much as 100 times more nitric oxide than non- ulcerative colitis controls. In light of your understanding of the nitric oxide signal transduction pathway, interpret these findings.

Question 23

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)on the cytoplasmic side of the plasma membrane.
B)at the outer cell surface.
C)within the cytoplasm of the cell.
D)within the nucleus of the cell.
E)all of the above

Question 24

The key mediators of apoptosis are the .

Question 25

A type of programmed cell death associated with DNA fragmentation and caspases is known as .

Question 26

The Ga- subunit is responsible for activation of .

Question 27

IL- 2 is a growth factor that acts on

A)T lymphocytes.
B)embryonic cells.
C)muscle cells.
D)macrophages.
E)epithelial cells.

Question 28

In animal eggs, once fertilization occurs, are the second messengers that trigger egg activation.

Question 29

Which of the following statements regarding Fas- mediated programmed cell death is false?

A)Fas ligand and receptor interaction results in the recruitment of adaptor proteins in the target cell.
B)The capase cascade results in the cleavage of the proteins within the target cell.
C)Capases are activated in the process.
D)It ultimately results in death of the cell.
E)Fas ligand binding with Fas receptor stimulates a specific G protein.

Question 30

Killer lymphocytes can elicit self- destruct mechanisms in target cells by interacting with

A)adaptor proteins.
B)Fas receptors.
C)Fas ligand.
D)procaspase.
E)Ras ligand.

Question 31

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.
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)associated with mitochondria.
B)in the nucleus.
C)associated with the ER.
D)on the cell surface.
E)within the cell.

Question 32

Which hormone is not an amino acid derivative?

A)norepinephrine
B)epinephrine
C)prostaglandin
D)thyroxine
E)histamine

Question 33

nucleotides are common signals in animal cells, but not in plant cells.

Question 34

are genetically engineered proteins that allow cytosolic calcium fluxes to be observed by an increase in fluorescence.

Question 35

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)The toxin, by altering Gs, keeps intracellular cAMP levels high and doesn't allow them to decrease.
E)Cholera toxin alters Gs so that it no longer hydrolyzes GTP.

Question 36

A developing organism's failure to produce muscle tissue is most likely due to

A)underdevelopment of the endoderm.
B)missing chromosomes.
C)adenylate cyclase mutations.
D)fibroblast growth factor receptor mutations.
E)underdevelopment of the ectoderm.

Question 37

Which of the following pairings is NOT correct?

A)phospholipase C- inositol triphosphate
B)calmodulin- calcium ions
C)phospholipase C- diacylglycerol (DAG)
D)adenylyl cyclase- ATP

Question 38

If one homogenizes liver cells, separates the membranes from the cytoplasm, and then adds epinephrine to only the cytoplasmic portion,

A)cAMP will be produced.
B)adenylyl cyclase will be activated.
C)G- proteins will be activated.
D)calcium ions will be released.
E)none of the above

Question 39

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.
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)glycogen breakdown
B)increased cell division
C)decreased protein synthesis
D)glucose 6- phosphate polymerization
E)all of the above