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Molecular Cell Biology Jessica > chapter 16 study questions > Flashcards

chapter 16 study questions Flashcards

1
Q

. Signaling by the steroid hormone estrogen is an example of _______ signaling.

a. autocrine
b. endocrine
c. paracrine d. direct cell-to-cell
e. electrical

A

b. endocrine

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2
Q

. Signaling by neurotransmitters is an example of _______ signaling.

a. autocrine
b. endocrine
c. paracrine
d. direct cell-to-cell
e. electrical

A

c. paracrine

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3
Q

. Stimulation of T lymphocytes, leading to their synthesis of a growth factor resulting in T lymphocyte proliferation, is an example of _______ signaling.

a. autocrine
b. endocrine
c. paracrine
d. direct cell-to-cell
e. electrical

A

a. autocrine

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4
Q

Signaling by cadherins is an example of _______ signaling.

a. autocrine
b. endocrine
c. paracrine
d. direct cell-to-cell
e. electrical

A

d. direct cell-to-cell

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5
Q

The hormone that triggers insect metamorphosis from larva to adult is

a. ecdysone.
b. aldosterone.
c. retinoic acid.
d. epidermal growth factor (EGF).
e. activin.

A

a. ecdysone.

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6
Q
  1. Nitric oxide(NO) is a paracrine signal molecule because it

a. is slow to diffuse.
b. is produced in very small quantities.
c. is unstable, with a short half life.
d. binds to cell surface receptors that are very plentiful.
e. stimulates the same cell type that produces it.

A

c. is unstable, with a short half life.

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7
Q
  1. NO-synthase produces NO from the amino acid

a. lysine.
b. histidine.
c. arginine.
d. serine.
e. citrulline

A

c. arginine

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8
Q
  1. Fibroblasts are stimulated to proliferate and heal a wound by

a. EGF.
b. NGF.
c. PDGF.
d. NO.
e. CO

A

c. PDGF

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9
Q
  1. All eicosanoids are synthesized from

b. arachidonic acid.
c. prostaglandin.
d. thromboxane A.
e. tyrosine.

A

b. arachidonic acid.

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10
Q
  1. The effect of acetylcholine on heart muscle cells is to

a. stimulate one contraction.
b. increase the rate of beating.
c. decrease the rate of beating.
d. relax the heart.
e. None of the above

A

c. decrease the rate of beating.

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11
Q

. The major function of cAMP in animal cells is to activate

a. adenylyl cyclase.
b. protein kinase A.
c. protein kinase C.
d. tyrosine kinases.
e. protein kinase B

A

b. protein kinase A.

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12
Q

. Which of the following is considered a second messenger?

a. cAMP
b. IP3
c. Calcium
d. Both a and b
e. All of the above

A

e. All of the above

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13
Q
  1. Protein kinase A regulates glycogen metabolism by _______ glycogen synthase and _______ glycogen phosphorylase. a. activating; activating
    b. inactivating; inactivating
    c. activating; inactivating
    d. inactivating; activating
    e. activating; stimulating degradation of
A

d. inactivating; activating

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14
Q

Rhodopsin in the vertebrate retinal photoreceptor cells results in a change in the second messenger _______, leading to the opening of ion channels in the plasma membrane and the production of a nerve impulse.

a. Ca2+
b. cAMP
c. cGMP
d. IP3
e. PIP2

A

c. cGMP

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15
Q

. MAP kinase is an abbreviation for _______ protein kinase.

a. microtubule-associated
b. mitogen-activated
c. mitosis-activating
d. mitosis-associated
e. None of the above

A

b. mitogen-activated

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16
Q

. Which of the following is an example of endocrine signaling?

a. Epinephrine release by motor neurons at the neuromuscular junction and binding to receptors on adjacent skeletal muscle cells
b. Antigen stimulation of T lymphocytes leading to the stimulation and synthesis of a growth factor that drives their own proliferation
c. Insulin release by β cells in the pancreas mediating an effect of glucose uptake by muscle cells
d. None of the above

A

c. Insulin release by β cells in the pancreas mediating an effect of glucose uptake by muscle cells

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17
Q

Which of the following hormones is (are) not synthesized from cholesterol? a. Testosterone

b. Progesterone
c. Corticosteroids
d. None of the above

A

d. None of the above

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18
Q

Which of the following is true in reference to G protein signaling?

a. Hormone binding induces an interaction of the receptor with the G protein, stimulating the release of GDP and the exchange of GTP on the α subunit.
b. Once activated, the GTP-bound α subunit dissociates from βγ and interacts with its target.
c. Activity of the α subunit is terminated by the hydrolysis of GTP to GDP.
d. All of the above

A

d. All of the above

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19
Q

Which of the following is not a commonly observed consequence of the binding of a signaling molecule to its cell surface receptor?

a. Receptor dimerization
b. Receptor phosphorylation
c. Conformational changes in the receptor
d. Increased synthesis of the receptor

A

d. Increased synthesis of the receptor

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20
Q

SH2 domains are

a. protein domains that bind phosphotyrosine-containing peptides.
b. the domains on receptor protein-tyrosine kinases that contain the phosphorylated tyrosine.
c. domains that mediate the dimerization of receptor protein-tyrosine kinases.
d. the domains on receptor protein-tyrosine kinases that possess the kinase activity.

A

a. protein domains that bind phosphotyrosine-containing peptides.

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21
Q

Cyclic AMP (cAMP) is synthesized from ATP by the action of

a. phosphodiesterase.
b. phosphorylase kinase.
c. adenylyl cyclase.
d. protein kinase A (PKA)

A

c. adenylyl cyclase.

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22
Q

. Most of the effects of cyclic AMP (cAMP) in the cell are mediated by

a. protein kinase A.
b. ion channels.
c. protein kinase C.
d. cAMP phosphodiesterase

A

c. adenylyl cyclase.

23
Q

. Most of the effects of cyclic AMP (cAMP) in the cell are mediated by

a. protein kinase A.
b. ion channels.
c. protein kinase C.
d. cAMP phosphodiesterase

A

a. protein kinase A.

24
Q

. Which of the following statements about protein kinase A (PKA) is false?

a. In the inactive state, PKA exists as a tetramer of two regulatory (R) and two catalytic (C) subunits.
b. PKA binds a total of four molecules of cAMP, one on each of the four subunits.
c. PKA binds a total of four molecules, two molecules on each of the two regulatory (R) subunits.
d. Once activated, the catalytic (C) subunits dissociate and activate target molecules

A

b. PKA binds a total of four molecules of cAMP, one on each of the four subunits.

25
Q

. The MEK kinase (MAP kinase/ERK kinase) is unusual in that it

a. is activated by a kinase.
b. lies downstream of G protein-coupled receptors.
c. is a dual-specificity kinase, having the ability to phosphorylate both threonines and tyrosines.
d. activates a kinase.

A

c. is a dual-specificity kinase, having the ability to phosphorylate both threonines and tyrosines.

26
Q

a. the Wingless (Wnt) signaling pathway.
b. the JAK/STAT pathway.
c. the Notch pathway.
d. the pathway leading to vulval development in C. elegans

A

c. the Notch pathway.

27
Q

yclic AMP (cAMP) is synthesized from ATP by the action of

a. phosphodiesterase.
b. phosphorylase kinase.
c. adenylyl cyclase.
d. protein kinase A (PKA).

A

c. adenylyl cyclase.

28
Q

. Most of the effects of cyclic AMP (cAMP) in the cell are mediated by

a. protein kinase A.
b. ion channels.
c. protein kinase C.
d. cAMP phosphodiesterase

A

a. protein kinase A.

29
Q

. Which of the following statements about protein kinase A (PKA) is false?

a. In the inactive state, PKA exists as a tetramer of two regulatory (R) and two catalytic (C) subunits.
b. PKA binds a total of four molecules of cAMP, one on each of the four subunits.
c. PKA binds a total of four molecules, two molecules on each of the two regulatory (R) subunits.
d. Once activated, the catalytic (C) subunits dissociate and activate target molecules

A

b. PKA binds a total of four molecules of cAMP, one on each of the four subunits.

30
Q

The MEK kinase (MAP kinase/ERK kinase) is unusual in that it
a. is activated by a kinase.
b. lies downstream of G protein-coupled receptors.
c. is a dual-specificity kinase, having the ability to phosphorylate both threonines and tyrosines.
d. activates a kinase.
Textbook Reference

A

c. is a dual-specificity kinase, having the ability to phosphorylate both threonines and tyrosines.

31
Q
  1. Heterotrimeric G proteins are not the only guanine nucleotide-binding proteins. Which of the following represents a family of more than 50 small GTP-binding proteins?
    a. Ras
    b. ERK
    c. Raf
    d. Smad
A

a. Ras

32
Q

The IP3 produced by phospholipase C acts to

a. open calcium channels in the plasma membrane.
b. open calcium channels in the endoplasmic reticulum.
c. activate IP3-dependent kinases.
d. activate protein kinase C.
e. open channels in mitochondria

A

b. open calcium channels in the endoplasmic reticulum.

33
Q

Diacylglycerol and calcium activate

a. protein kinase A.
b. protein kinase C.
c. PI 3-kinase.
d. Ca2+/calmodulin-dependent kinase.
e. a tyrosine kinase

A

b. protein kinase C.

34
Q

Calcium stimulates many cellular enzymes by binding to a calcium-binding protein called

a. calcineurin.
b. calcinectin.
c. calmodulin.
d. calbindin.
e. cadherin

A

c. calmodulin

35
Q

. MAP kinase signal cascades are often organized into functional groups or cassettes by a. scaffold proteins.

b. binding of SH2 domains to each other.
c. lipid rafts.
d. binding MAP kinase-responsive genes.
e. binding to the nuclear envelope

A

. scaffold proteins.

36
Q

G protein-coupled receptors are important molecules involved in signal transduction. Which of the following statements best describes G protein-coupled receptors?

G protein-coupled receptors are only activated by steroid hormones.

 G protein-coupled receptors generally contain seven membrane-spanning αhelices.

 G protein-coupled receptors bind only guanine nucleotides.

 G protein-coupled receptors bind both adenine and guanine nucleotides.
A

G protein-coupled receptors generally contain seven membrane-spanning αhelices.

37
Q

An example of signaling by direct cell-cell interactions is
the pathway leading to vulval development in C. elegans.

 the Notch pathway.

 the Wingless (Wnt) signaling pathway.

 the JAK/STAT pathway.
A

the Notch pathway.

38
Q

Which of the following steroid hormones is (are) not secreted by the gonads?
Testosterone

 Progesterone

 Corticosteroids

 Estrogen
A

Corticosteroids

39
Q

The term “paracrine signaling” refers to
signaling between cells located far from each other.

 stimulation of a cell by substances produced by the cell itself.

 signaling between cells located close to each other.

 signaling between parenchyma cells.
A

signaling between cells located close to each other.

40
Q

Which of the following is not a commonly observed consequence of the binding of a signaling molecule to its cell surface receptor?
Increased synthesis of the receptor

 Receptor phosphorylation

 Receptor dimerization

 Conformational changes in the receptor
A

Increased synthesis of the receptor

41
Q

Which of the following hormones is (are) not synthesized from cholesterol?
Testosterone

 Progesterone

 Corticosteroids

 None of the above
A

None of the above

42
Q

Which of the following is true in reference to G protein signaling?
Hormone binding induces an interaction of the receptor with the G protein, stimulating the release of GDP and the exchange of GTP on the α subunit.
Once activated, the GTP-bound α subunit dissociates from βγ and interacts with its target.

 Activity of the α subunit is terminated by the hydrolysis of GTP to GDP.

 All of the above
A

All of the above

43
Q

Which of the following is not a therapeutic effect of aspirin?
Reducing the chance of acquiring colon cancer

 Stimulation of the growth of fibroblasts at the site of a wound, thus aiding the healing process

 Reduction of inflammation and pain

 Reduction of blood clotting
A

Stimulation of the growth of fibroblasts at the site of a wound, thus aiding the healing process

44
Q

The MEK kinase (MAP kinase/ERK kinase) is unusual in that it
activates a kinase.

 is activated by a kinase.

 lies downstream of G protein-coupled receptors.

an is a dual-specificity kinase, having the ability to phosphorylate both threonines d tyrosines.

A

an is a dual-specificity kinase, having the ability to phosphorylate both threonines d tyrosines.

45
Q

Integrins are transmembrane proteins that connect
microtubules to actin filaments.

 the nuclear laminae to cytoplasmic kinases.

 focal adhesions to hemidesmosomes.

 the extracellular matrix to the cytoskeleton.
A

the extracellular matrix to the cytoskeleton.

46
Q

Heterotrimeric G proteins are not the only guanine nucleotide-binding proteins. Which of the following represents a family of more than 50 small GTP-binding proteins?
Ras

 Smad

 ERK

 Raf
A

Ras

47
Q

Most of the effects of cyclic AMP (cAMP) in the cell are mediated by
ion channels.

 cAMP phosphodiesterase.

 protein kinase C.

 protein kinase A.
A

protein kinase A.

48
Q 
Cyclic AMP (cAMP) is synthesized from ATP by the action of
     phosphodiesterase.
 phosphorylase kinase.

 adenylyl cyclase.

 protein kinase A (PKA).
A

adenylyl cyclase.

49
Q

Which of the following is an example of endocrine signaling?
Epinephrine release by motor neurons at the neuromuscular junction and binding to receptors on adjacent skeletal muscle cells
Antigen stimulation of T lymphocytes leading to the stimulation and synthesis of a growth factor that drives their own proliferation
Insulin release by β cells in the pancreas mediating an effect of glucose uptake by muscle cells

 None of the above
A

Insulin release by β cells in the pancreas mediating an effect of glucose uptake by muscle cells

50
Q

________________________________________
What is the difference between neurotransmitters and neuropeptides?
Some neuropeptides can act on distant cells, whereas neurotransmitters cannot.

 Neurotransmitters are small protein molecules and neuropeptides are large ones.

 Neurotransmitters are small hydrophilic molecules and neuropeptides are small proteins.

 Neuropeptides are generated by neuronal cells but do not transmit signals.
A

Neurotransmitters are small hydrophilic molecules and neuropeptides are small proteins.

51
Q

Receptor protein-tyrosine kinases represent critical molecules involved in growth and differentiation though phosphorylation of target substrates on tyrosine residues. Which of the following is not a common structural feature of all receptor protein-tyrosine kinases?
A single transmembrane α helix

 An N-terminal extracellular ligand-binding domain

 A single polypeptide

 A cytosolic C-terminal domain with protein-tyrosine kinase activity
A

A single polypeptide

52
Q

Which of the following statements about protein kinase A (PKA) is false?
PKA binds a total of four molecules of cAMP, one on each of the four subunits.

 In the inactive state, PKA exists as a tetramer of two regulatory (R) and two catalytic (C) subunits.

 PKA binds a total of four molecules, two molecules on each of the two regulatory (R) subunits.

 Once activated, the catalytic (C) subunits dissociate and activate target molecules.
A

PKA binds a total of four molecules of cAMP, one on each of the four subunits.

53
Q

Which of the following is true regarding heterotrimeric G proteins in a resting state?
GTP is bound to the α subunit in complex with both the β and γ subunits.

 The β subunit is bound to GDP in complex with both the α and γ subunits.

 G proteins are in complex with G protein-coupled receptors.

 GDP is bound to the α subunit in complex with both the β and γ subunits.
A

GDP is bound to the α subunit in complex with both the β and γ subunits.

Molecular Cell Biology Jessica (33 decks)

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