Deck 13: Biochemical Signaling

Question 1

Matching
The gland that is predominately responsible for producing the hormone that is released in response to consumption of a meal particularly high in carbohydrates.

A)receptors
B)phosphoinositide
C)rhodopsin
D)calmodulin
E)insulin
F)hypothalamus
G)cortisol
H)adrenal cortex
I)cyclic AMP
J)RasGAP
K)islets of Langerhans
L)adenylate cyclase (AC)
M)receptor tyrosine kinase (RTK)

Answer 1

islets of Langerhans

Question 2

Matching
The ____ signaling pathway relies on GTP dependent hydrolysis for subsequent synthesis of cAMP.

A)receptors
B)phosphoinositide
C)rhodopsin
D)calmodulin
E)insulin
F)hypothalamus
G)cortisol
H)adrenal cortex
I)cyclic AMP
J)RasGAP
K)islets of Langerhans
L)adenylate cyclase (AC)
M)receptor tyrosine kinase (RTK)

Answer 2

adenylate cyclase (AC)

Question 3

The $\alpha$ cells of the islets of Langerhans secrete _____ in response to ____ glucose levels in the liver.

A)insulin; low
B)insulin; elevated
C)glucagon; low
D)glucagon; elevated
E)somatostatin; elevated

Answer 3

glucagon; low

Question 4

Matching
The first G protein-coupled receptor (GPCR)to be structurally analyzed at the atomic level was _____.

A)receptors
B)phosphoinositide
C)rhodopsin
D)calmodulin
E)insulin
F)hypothalamus
G)cortisol
H)adrenal cortex
I)cyclic AMP
J)RasGAP
K)islets of Langerhans
L)adenylate cyclase (AC)
M)receptor tyrosine kinase (RTK)

Question 5

The insulin signaling pathway includes which of the following steps?

A)ligand-induced dimerization of the receptor and phosphorylation of IRS-1 and/or IRS-2 proteins
B)autophosphorylation and phosphorylation of IRS-1 and/or IRS-2 proteins
C)IRS-1-induced dimerization of the receptor, autophosphorylation, and phosphorylation of SH2 domains
D)autophosphorylation and dephosphorylation of IRS-1 and/or SH2 domains
E)none of the above

Question 6

The ability of receptors to adapt to long-term stimulation by responding to changes in stimulation levels rather than absolute values of stimulation is called

A)dual-specificity.
B)intrasteric sensitivity.
C)autoinhibition.
D)desensitization.
E)switch regional detection.

Question 7

Phospholipase C cleaves PIP₂, resulting in an increased cytosolic concentration of
I.IP₃ (inositolpolyphosphate-3)
II.protein kinase C
III.cAMP
IV.Ca²⁺

A)I only
B)II only
C)I, III
D)I, IV
E)IV only

Question 8

Which of the following proteins is a phosphatase activated by Ca²⁺ essential for T cell proliferation?

A)calcineurin
B)calmodulin (CaM)
C)rhodopsin
D)RasGAP
E)MAPK

Question 9

Matching
Proteins that bind molecules and elicit a cellular response are called _____.

A)receptors
B)phosphoinositide
C)rhodopsin
D)calmodulin
E)insulin
F)hypothalamus
G)cortisol
H)adrenal cortex
I)cyclic AMP
J)RasGAP
K)islets of Langerhans
L)adenylate cyclase (AC)
M)receptor tyrosine kinase (RTK)

Question 10

Matching
A release of _____ would result in the stimulation of the liver to synthesize glycogen.

A)receptors
B)phosphoinositide
C)rhodopsin
D)calmodulin
E)insulin
F)hypothalamus
G)cortisol
H)adrenal cortex
I)cyclic AMP
J)RasGAP
K)islets of Langerhans
L)adenylate cyclase (AC)
M)receptor tyrosine kinase (RTK)

Question 11

Matching
The hormone _____ is responsible for a variety of actions including the ability to cope with stress.

A)receptors
B)phosphoinositide
C)rhodopsin
D)calmodulin
E)insulin
F)hypothalamus
G)cortisol
H)adrenal cortex
I)cyclic AMP
J)RasGAP
K)islets of Langerhans
L)adenylate cyclase (AC)
M)receptor tyrosine kinase (RTK)

Question 12

The interaction (cross-talk)of various signaling pathways

A)allows for dual-specificity within different cell types.
B)is necessary for effective signal transduction.
C)occurs during autoinhibition of a pathway.
D)accounts for the ability of a signaling pathway to undergo desensitization.
E)can be minimized by scaffold proteins.

Question 13

Matching
Cytosolic calcium ion levels are altered by the _____ signaling pathway.

A)receptors
B)phosphoinositide
C)rhodopsin
D)calmodulin
E)insulin
F)hypothalamus
G)cortisol
H)adrenal cortex
I)cyclic AMP
J)RasGAP
K)islets of Langerhans
L)adenylate cyclase (AC)
M)receptor tyrosine kinase (RTK)

Question 14

Insulin binds to a receptor that
I.is coupled to a G protein.
II.possesses tyrosine kinase activity.
III.possesses serine/threonine phosphatase activity.
IV.interact with proteins homologous to Src

A)I, II, III
B)II only
C)I, III
D)II, IV
E)I, IV

Question 15

Heterotrimeric G proteins
I.consist of three subunits, G $\alpha$ , G $\beta$ , and G $\gamma$ .
II.function as an autoinhibtory segment.
III.can function as a mediator to adenylate cyclase activity.
IV.are anchored to the cytoplasmic side of the membrane.

A)I, II, IV
B)I, III, IV
C)I, IV
D)I, III
E)I only

Question 16

Matching
The ____ signaling pathway undergoes autophosphorylation resulting in kinase activation.

A)receptors
B)phosphoinositide
C)rhodopsin
D)calmodulin
E)insulin
F)hypothalamus
G)cortisol
H)adrenal cortex
I)cyclic AMP
J)RasGAP
K)islets of Langerhans
L)adenylate cyclase (AC)
M)receptor tyrosine kinase (RTK)

Question 17

Matching
A molecule that often functions as a second messenger is ______.

A)receptors
B)phosphoinositide
C)rhodopsin
D)calmodulin
E)insulin
F)hypothalamus
G)cortisol
H)adrenal cortex
I)cyclic AMP
J)RasGAP
K)islets of Langerhans
L)adenylate cyclase (AC)
M)receptor tyrosine kinase (RTK)

Question 18

Matching
Isoproterenol functions as an agonist for receptors that bind hormones synthesized in the ___.

A)receptors
B)phosphoinositide
C)rhodopsin
D)calmodulin
E)insulin
F)hypothalamus
G)cortisol
H)adrenal cortex
I)cyclic AMP
J)RasGAP
K)islets of Langerhans
L)adenylate cyclase (AC)
M)receptor tyrosine kinase (RTK)

Question 19

The $\beta$ cells of the islets of Langerhans secrete ______ in response to ______ glucose levels in the muscle and/or adipose tissue.

A)insulin; low
B)insulin; elevated
C)glucagon; low
D)glucagon; elevated
E)somatostatin; elevated

Question 20

Cancer causing viruses often contain:
I.oncogenes.
II.genes encoding variant proteins.
III.genes encoding cell proliferation inhibitors.
IV.genes capable of inducing malignant transformation.

A)I only
B)III only
C)IV only
D)I, II, IV
E)I, II, III, IV

Question 21

Which of the following proteins has a structural motif called an "EF hand"?

A)insulin
B)calmodulin (CaM)
C)receptor tyrosine kinases (RTK)
D)cAMP-dependent protein kinase
E)scaffold proteins

Question 22

Which of the following sets of terms has a member that does not belong?

A)rhodopsin - heterotrimeric G protein - desensitization
B)autoinhibitor segment - receptor tyrosine kinase - SH2
C)propranolol - β-adrenoreceptor - antagonist
D)transcortin - aldosterone - adrenal cortex
E)adenylate cyclase - cholera toxin - heterotrimeric G protein

Question 23

Catecholamines mediate their effects through
I.α-adrenoreceptors.
II.β-adrenoreceptors.
III.receptor tyrosine kinases.
IV.monomeric G protein receptors
.

A)I only
B)II only
C)I and II
D)III and IV
E)IV only

Question 24

Which of the following statements concerning the action of G proteins on adenylate cyclase is true?
I.G proteins always serve to activate adenylate cyclase.
II.G proteins always serve to inhibit adenylate cyclase.
III.Some G proteins activate adenylate cyclase, while others inhibit it.
IV.G proteins do not act on adenylate cyclase at all.

A)I only
B)II, III
C)I, III
D)II only
E)III only

Question 25

Which of the following is (are)an advantage(s)of protein phosphorylation in regards to biochemical signaling?
I.Phosphorylation is rapid and specific.
II.Phosphorylation is enzymatically reversible.
III.Phosphorylation can be amplified by cascade systems.
IV.Phosphorylation results in covalent modification of enzymes.

A)I, II, III, IV
B)II, III, IV
C)II, III
D)I, II
E)III only

Question 26

Which of the following is (are)associated with cAMP binding to cAMP-dependent protein kinase A?
I.cAMP binds to the regulatory subunits.
II.Tetrameric regulatory subunits and catalytic subunits dissociate.
III.Catalytic subunits phosphorylate multiple targets with specific serine and threonine residues.
IV.cAMP is membrane bound via phosphoinositol attachment.

A)I, II, III, IV
B)I, II, III
C)I, II
D)II, III, IV
E)III, IV

Question 27

Considering the same unidentified proteins discussed in the question 32 above (UPS-1 through UPS-3)what can you conclude from the following observations and the knowledge you gained in this chapter? OBSERVATIONS:
1)UPS-1 is capable of autophosphorylation.
2)UPS-2 becomes phosphorylated only when UPS-1 is phosphorylated.
3)UPS-2, when phosphorylated interacts with UPS-3 and activates the Ras protein.
4)Recombinant UPS-2 protein that has a mutation resulting in the replacement of tyrosine for serine in the binding region loses all function.
5)The proteins Jun and Fos are expressed at high levels in the presence of UPS-1,2,3.

A)The UPS signaling system functions as a heterotrimeric G protein signaling cascade.
B)Sugarish appears to solicit a similar insulin response to that expected from glucose.
C)Sugarish must be sensitive to the phosphoinositide pathway.
D)Calmodulin (CaM)would likely alter the activity of the UPS proteins.
E)None of the above are possible conclusions.

Question 28

Which of the following functions as a regulatory protein by dephosphorylating activated enzymes?

A)receptor tyrosine kinase
B)phosphoprotein phosphatase
C)heterotrimeric G protein phosphorylase
D)guanine nucleotide exchange factor
E)Sos protein

Question 29

Which of the following are activated either directly or indirectly by a heterotrimeric G protein subunit?
I.phospholipase C
II.Herceptin
III.calmodulin (CaM)sensitive kinase
IV.MAPK

A)I, II, III, IV
B)I, II
C)I, III
D)II, III, IV
E)I, II, IV

Question 30

Somatostatin
I.inhibits the release of insulin.
II.inhibits the release of glucagon.
III.stimulates the release of insulin.
IV.stimulates the release of glucagon.

A)I only
B)II only
C)I and II
D)III and IV
E)IV only

Question 31

Which of the following is (are)the result of insulin binding to its receptor?
I.MAPK activation, which regulates gene expression via Fos, Jun and Myc.
II.PI3K activation leading to an increase in glucose transport.
III.High affinity binding of SH2 domains to phosphorylated tyrosines.
IV.Autophosphorylation resulting in activation of tyrosine kinase.

A)II, III, IV
B)I, II, III, IV
C)II, III
D)I, II
E)III only

Question 32

Which of the following are produced in the adrenal cortex?
I.Glucorticoids
II.mineralcorticoides
III.androgens
IV.estrogens

A)I only
B)I, II
C)II only
D)II, IV
E)I, II, III, IV

Question 33

The activity of protein kinase A is affected by which of the following?
I.caffeine
II.levels of cAMP
III.phosphodiesterases
IV.cholera toxin

A)I only
B)II only
C)I, IV
D)I, II, III
E)I, II, III, IV

Question 34

Which of the following increases the affinity of SH2 binding to phosphor-tyrosine?

A)The absence of a Ser or Thr residue in the binding region.
B)The presence of an Arg residue deep in the binding pocket.
C)The presence of an Arg residue near the binding pocket entrance.
D)The absence of a Ser residue deep in the binding pocket.
E)None of the above.

Question 35

Recently a researcher has discovered several unidentified proteins (UPS-1 through UPS-3)that are up regulated (produced in higher levels)by the cell in response to the inclusion of high levels of an artificial sweetener called "sugarish".The research ran a PAGE gel of the protein samples after the cells were treated with different concentrations of "sugarish" (0-5 nm).One sample was also treated with the detergent SDS.The results are shown below.Which of the following are possible conclusions given these results and the knowledge you have gained from this chapter? I.UPS-1 functions as a dimer.
II.UPS-1 interacts with UPS-2.
III.UPS-1 interacts with UPS-3.
IV.UPS-2 interacts with UPS-3.

A)I, II, III, IV
B)II, III, IV
C)I, II
D)I, III
E)II, III

Question 36

Based on the following figure, which of the following are possible? I."A" could be adenylate cyclase.
II."B" is a receptor protein.
III."C" could be an inactive Ras protein.
IV."D" could be an SH2 domain.

A)I, II, III, IV
B)I, II, III
C)II, III, IV
D)I only
E)III only

Question 37

Ras is an example of
I.a protein anchoted by prenylation.
II.a heterotrimeric G protein.
III.a kinase activated protein.
IV.a GTP dependent protein.

A)I, II, III, IV
B)I, III, IV
C)I, III
D)II, III, IV
E)IV only

Question 38

The virulent form of bubonic plague carries a protein called YopH.Which of the following is true?

A)YopH functions as a MAPK specific inhibitor.
B)YopH functions as a Ras inhibitor.
C)YopH functions as a receptor tyrosine kinase.
D)YopH functions as a protein tyrosine phosphatase.
E)YopH functions as β propeller.

Question 39

Which of the following generalizations explains how anabolic steroids can affect muscle growth?

A)Anabolic steroids increase the level of testosterone, a hormone predominately found in males.
B)Anabolic steroids easily pass through the membrane and bind steroid receptors which migrate to the nucleus and function as a transcription factor.
C)Anabolic steroids are water soluble and can transport to the muscle tissue readily.
D)Anabolic steroids alter the phosphoinositide pathway, thereby increasing levels of calcium in the cytosol and subsequently increase the strength of muscle contraction.
E)None of the above is correct.

Question 40

Which of the following hormones functions by binding to receptors that function directly as transcription factors?

A)steroids
B)insulin
C)epinephrine
D)glucagon
E)somatostatin

Question 41

Which of the following activities would lead to a decrease in the level of IP₃ in the cytosol?

A)increased activity of inositol polyphosphate 5-phosphatase
B)increased activity of phospholipase C
C)increased activation of protein kinase C
D)increased Ca²⁺ concentration
E)all of the above

Question 42

Anthrax toxin functions by altering levels of cAMP.The toxin also contains an edema factor, which requires the activity of calmodulin (CaM)for proper function.Based on this information, which of the following can you conclude?

A)The toxin alters cAMP dependent cell signaling.
B)Calcium levels affect the function of the edema factor.
C)Unlike other toxins, the anthrax toxin does not function by altering biochemical signaling.
D)A and B
E)A and C

Question 43

Autoinhibition in the SH2 and SH3 domains

A)occurs when a SH2 phospho-Tyr forms a salt bridge with an Arg on SH3.
B)occurs when a SH2 phospho-Tyr binds a Pro segment on the SH3 domain, therefore blocking the active site and burying the required Tyr.
C)occurs when a salt bride forms between the active site phosphor-Tyr on SH3 and the Glu on the activation loop.
D)occurs when the salt bridge between Glu and Arg is broken.
E)None of the above is correct.

Question 44

Scaffold proteins limit

A)oncogene transfer.
B)MAPK activity.
C)cross-talk.
D)cell differentiation.
E)signal amplification.

Question 45

Sildenafil (Viagra)

A)inhibits activity of a phosphoprotein phosphatase.
B)increases the relative concentration of cGMP.
C)increases the relative concentration of nitric oxide in the blood.
D)A, B, and C
E)A and B

Question 46

Oncogenes
I.function as cell cycle inhibitors.
II.encode a protein which block cell cycle inhibition.
III.are expressed by cells that have higher levels of human growth hormone.
IV.can function as transcription factors.

A)I, III, IV
B)II, III
C)III, IV
D)II, IV
E)II

Question 47

Which of the following best describe the mechanism of calmodulin (CaM)mediated activation?

A)Ca²⁺ binding to calmodulin (CaM)results in conformational change that exposes a hydrophobic patch capable of binding to calcium sensitive protein kinase
B)a conformational change induced by the binding of Ca²⁺ results in the release of the phosphate group in calmodulin (CaM)
C)calmodulin (CaM)sensitive protein kinase dimerizes forming a joint active site capable of tightly binding Ca²⁺
D)phosphorylation of a tyrosine on calmodulin induced a conformational change that results in release of Ca²⁺ from the cytosol.
E)none of the above.

Question 48

Which of the following is always true of hormones?

A)Hormones always bind membrane bound receptors.
B)Hormones elicit specific cellular responses.
C)Hormones are secreted from a gland via a robust network of ducts.
D)The release of hormones is influenced by adrenal receptors.
E)All of the above are true.

Question 49

Which of the following correctly states an essential step in the function of heterotrimeric G protein function?

A)A cascade of events must occur that ultimately activate protein kinase C.
B)Binding of a hormone to a receptor must signal the exchange of GDP for GTP.
C)Binding of GTP to the receptor protein must induce a change in conformation of the receptor.
D)Binding of cAMP to the α subunit of the G protein must initiate translocation of the subunit.
E)All of the above are correct.

Question 50

Which of the following describes the similarity between the following words? DAG, cAMP, IP3

A)All of them induce conformational changes in PKA.
B)All of them activate adenylate cyclase.
C)All of them require phosphorylation in order to function.
D)All of them function as second messengers.
E)All them result from the activity of phosphoprotein lipase.