Deck 23: Signal

Question 1

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

Answer 1

receptors

Question 2

The following questions refer to the structure below:

-What is the name of this molecule?

A) ATP
B) GTP
C) GMP
D) AMP
E) cAMP

Answer 2

cAMP

Question 3

The following questions refer to the structure below:

-This molecule often serves as a

A) primary messenger
B) secondary messenger
C) kinase inhibitor
D) catalytic subunit
E) none of the above

Answer 3

secondary messenger

Question 4

The following questions refer to the structure below:

-____ serves as a substrate of ___ to produce this molecule.

A) ATP; adenylate cyclase
B) ADP; adenylate cyclase
C) GDP; guanylate cylcase
D) GTP; G-protein
E) ADP; ATP synthase

Question 5

The following questions refer to the structure below:

-To affect cellular change this molecule

A) inhibits the catalytic subunit of protein kinase A
B) binds the regulatory subunit of protein kinase A and inhibits the enzyme's catalytic activity
C) binds the regulatory subunit of protein kinase A and encourages release of the enzyme's catalytic subunits
D) binds G-proteins to activate them when a hormone binds a G-protein coupled receptor

Question 6

Activation of a G protein in response to hormone binding requires binding of _____ to the _____ subunit.

A) GDP; $\beta$
B) GTP; $\alpha$
C) GDP; $\gamma$
D) GTP; $\beta$
E) GDP; $\alpha$

Question 7

What enzyme is activated by association with an active G protein?

A) adenylate cyclase
B) cAMP phosphodiesterase
C) protein kinase A
D) protein kinase G
E) all of the above

Question 8

What two amino acid residues are the targets of protein kinase A?

A) Asn and Gln
B) Thr and Ser
C) Tyr and Thr
D) Ser and Tyr
E) Cys and Ser

Question 9

Desensitization of a G protein-coupled receptor is caused by phosphorylation of the receptor by a specific kinase. What protein recognizes the phosphorylated receptor?

A) phospholipase C
B) the G protein $\gamma$ subunit
C) cAMP phosphodiesterase
D) adenosine receptor
E) arrestin

Question 10

The insulin receptor is of the ___________ type.

Question 11

The insulin receptor must itself be phosphorylated to be activated. The activation of the insulin receptor occurs through catalysis by protein kinase A.

A) Both sentences are true.
B) Both sentences are false.
C) The first sentence is true and the second sentence is false.
D) The first sentence is false and the second sentence is true.

Question 12

Which is NOT true of insulin?
I. Its receptors must dimerize for activation to occur
II. It recruits scaffolding proteins such as IRS which begins signal amplification
III. It influences cell growth by working through the MAP kinase pathway
IV. It activates lipases leading to release lipids from adipocytes

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

Question 13

How does insulin lower blood glucose following a meal?

A) It encourages carbohydrate breakdown in the bloodstream, and subsequent excretion through the renal system.
B) Released from the pancreas to the small intestine, it encourages carbohydrate breakdown in the digestive tract for easier excretion through the renal system.
C) It binds glucose in the bloodstream and assists in its excretion through the renal system.
D) It encourages glucose uptake into target cells by intracell signaling resulting in glucose transporter availability.
E) Both A and B are correct

Question 14

Which is NOT true of the AMPK pathway?

A) It is stimulated with elevated [ATP]/[AMP]
B) It inhibits gluconeogenesis
C) It can be regulated through PKA
D) It activates catabolic pathways

Question 15

You would expect the AMPK pathway to be activated when

A) blood [nutrients] are high
B) blood [insulin]/[glucagon] is high
C) blood [glucagon]/[insulin] is high
D) liver gluconeogenesis is high
E) Both A and B are correct

Question 16

Signal transduction pathways may affect cellular

A) metabolism
B) gene expression
C) cell division
D) apoptosis
E) All of the above

Question 17

Second messengers
I. include cGMP
II. are small, soluble molecules
III. are released or generated in response to extracellular signals
IV. include catecholamines

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

Question 18

Ligand binding to a receptor tyrosine kinase causes _____ of the receptor which then _____ the next protein in the signaling pathway.

A) methylation; hydrolyzes
B) hydrolysis; inhibits
C) autophosphorylation; phosphorylates
D) acylation; activates
E) none of the above

Question 19

By lacking an essential serine or tyrosine, proteins with pseudosubstrate domains regulate signaling pathways by blocking kinase

A) separation of regulatory subunits from catalytic subunits
B) phosphorylation
C) phosphatase ability
D) interaction with AMP
E) interaction with SH2 domains

Question 20

Signal transduction pathways may use ___ messengers or ___ cascades, both of which allow regulation, crosstalk and amplification of signaling pathways.

Question 21

Some cell signaling pathways, such as the toll-like receptors (TLRs), are expressed in all cell types. Most signaling pathways have "cross points" that allow them to modulate each other.

A) Both sentences are true
B) Both sentences are false
C) The first sentence is true and the second sentence is false
D) The first sentence is false and the second sentence is true

Question 22

The pseudokinase domain of JAK is reminiscent of

A) the catalytic subunit of adenylate cyclase
B) the catalytic subunit of PKA
C) the regulatory subunit of PKA
D) G-type proteins activated by GTP
E) autophosphorylating receptors such as G protein linked receptors

Question 23

STAT is a signal transduction protein that

A) must be phosphorylated to be activated
B) must dimerize to be activated
C) is dimerized through its SH2 domains
D) serves as a transcription factor
E) All of the above are correct

Question 24

What is common to both the insulin receptor and JAK/STAT receptor?

A) Both are similar to growth factor receptors
B) Both need to dimerize following ligand binding
C) Both autophosphorylate
D) Both A and B are correct
E) All of the above are correct

Question 25

SOCS (Suppressor of Cytokine Signaling) binds ___ and ____ it.

A) JAK; activates
B) STAT; activates
C) STAT; inhibits
D) JAK; inhibits
E) JAK; phosphorylates

Question 26

Through its activation in preadipocytes, the JAK-STAT pathway has shown a link between

A) inflammation and mitogenesis
B) obesity and mitogenesis
C) obesity and inflammation
D) obesity and diabetes
E) diabetes and cell growth

Question 27

ERK, JNK and p38

A) are MAP kinase pathway branches
B) respond to mitogens
C) may be responsible for some cancers
D) phosphorylate transcription factors
E) All the above are correct

Question 28

MAP kinases generally
I. work through the activation of heterotrimeric G-protein coupled receptors
II. require multiple phosphorylations to be activated
III. are specific tyrosine kinases
IV. include PKA among its cascade members

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

Question 29

How are heterotrimeric G-proteins and Ras similar?

A) Both work through the same receptor type
B) Both are cytosolic and not cell-membrane associated
C) Both exchange GDP for GTP for activation
D) Neither is involved in the MAP Kinase cascade
E) None of the above is correct

Question 30

Where are the ultimate targets of the Ras-dependent signaling cascade located within the cell?

A) cytoplasm
B) nucleus
C) endoplasmic reticulum
D) mitochondria
E) cell membrane

Question 31

Gleevec is a successful anti-leukemic that works by inhibiting the ___ pathway.

A) JAK-STAT
B) MAP kinase
C) phosphoinositol
D) toll-like receptor
E) cyclin-CDK

Question 32

Which includes an incorrect pathway constituent?

A) JAK, STAT, cAMP
B) heterotrimeric G protein, adenylate cyclase, PKA
C) insulin, IRS-1, GLUT vesicles
D) Ras, SOS, MEK
E) IP3, DAG, Ca+2

Question 33

Which is NOT true of toll-like receptor (TLR) signaling?

A) Lipopolysaccharides are common ligands
B) It commonly work through second messengers like cAMP
C) It modulates immune response
D) It exhibits relatively extensive cross talk with other pathways
E) Its modulation may be useful for autoimmune dysfunctions or cancer

Question 34

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

Question 35

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 36

The second messenger _____ opens Ca²⁺ channels in the endoplasmic reticulum.

A) inositol trisphosphate (IP3)
B) diacylglycerol
C) cAMP
D) cGMP
E) nitric oxide

Question 37

The action of phospholipase C produces the second messengers ___ and ___.

Question 38

In pathways in which activation of both PKA and PKC occurs, the receptor must dimerize and autophosphorylate. Both of these pathways employ a similar heterotrimeric G protein that associates with the receptor.

A) Both sentences are true
B) Both sentences are false
C) The first sentence is true and the second sentence is false
D) The first sentence is false and the second sentence is true

Question 39

The target of phospholipase C is a(n) ___ found in the ___.

A) phospholipid; cell membrane
B) protein; cell membrane
C) enzyme; cell membrane
D) phospholipid; endoplasmic reticulum
E) protein; nucleus

Question 40

____ are genes that code for proteins that encourage cell growth and survival, but when mutated may lead to overgrowth and tumor formation.

Question 41

The phosphoinositol pathway can respond to tumor promotors to elicit tumor formation. Tumor promoters are

A) primary messengers
B) activated by Ca+2
C) inhibited by particular G proteins
D) proteins that facilitate the growth of tumors
E) Both A and B are correct

Question 42

Phorbol esters stimulate the phosphoinositol pathway, leading to tumor promotion, by

A) mimicking Ca+2 and activating PKC
B) mimicking IP3 and activating PKC
C) mimicking IP3 and activating the endomembrane Ca+2 channel
D) mimicking DAG and activating PKC
E) activating PLC

Question 43

Particular Cyclin Dependent Kinases (CDKs) bind their specific cyclins, leading to regulation of cell growth and replication at particular times in the cell cycle. Both cyclins and CDKs are expressed only during the phase of the cell cycle at which they act.

A) Both sentences are true
B) Both sentences are false
C) The first sentence is true and the second sentence is false
D) The first sentence is false and the second sentence is true

Question 44

INK, Kip proteins and Cdc-25

A) inhibit or negatively regulate CDKs
B) would decrease cell growth and division
C) serve as substrates for CDKs
D) inhibit condensins
E) Both A and B are correct

Question 45

When bound to its specific CDK, one cyclin is apparently responsible for assembling metaphase chromosomes. The cyclin responsible for this assembly is likely Cyclin E, which peaks during the G1 phase of the cell cycle.

A) Both sentences are true
B) Both sentences are false
C) The first sentence is true and the second sentence is false
D) The first sentence is false and the second sentence is true

Question 46

Nitroglycerin has its positive cardiovascular effect by stimulating the production of ___, which increased ___.

A) cAMP; vasodilation
B) DAG; cardiac cell growth
C) cAMP; cardiac cell growth
D) cGMP; vasodilation
E) DAG; Ca+2 release to cardiac cells

Question 47

NOS is a synthetase that catalyzes the production of

A) nitrogen oxide (NO)
B) nitrous oxide (N2O)
C) nitrogen dioxide (NO2)
D) Both A and B are correct
E) All of the above are correct

Question 48

Which is NOT required for the production of NO gas in the vascular endothelium?

A) eNOS
B) electrons
C) cGMP
D) arginine
E) NADPH

Question 49

To effect vasodilation, NO

A) binds vascular endothelial guanylate cycles and activates it
B) binds vascular smooth muscle guanylate cyclase and activates it
C) binds vascular smooth muscle guanylate cyclase and inhibits it
D) binds vascular endothelial guanylate cyclase and inhibits it
E) Both A and B are correct

Question 50

In addition to the soluble form of guanylate cyclase, a transmembrane form is also present in the vasculature, where it serves as a receptor for ___, which also results in vasodilation.

A) insulin
B) catecholamines
C) growth factors
D) atrial natriuretic factor
E) cortisol

Question 51

PKG and PKA are similar in that both
I. are activated by a cyclic nucleotide monophosphate
II. have nucleotide-binding and kinase domains
III. release their catalytic subunits when activated
IV. phosphorylate downstream proteins to effect cellular change

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