Question 1

The auxin response factor (ARF) family members are believed to encode _______________.

Accepted Answer

A)  G proteins
B)  ubiquitins
C)  transcription factors
D)  gene repressorsE) All of the above
F) None of the above

Question 2

Which amino acids are known to be phosphorylated by protein kinases?

Accepted Answer

A)  tyrosine, threonine, glycine
B)  threonine, serine, tryptophan
C)  serine, threonine, tyrosine
D)  phenylalanine, serine, tyrosine
E)  serine, leucine, tyrosineF) C) and E)
G) All of the above

Question 3

Who was one of the first scientists to observe the effects of the plant hormone auxin?

Accepted Answer

A)  Gregor Mendel
B)  Charles Darwin
C)  Louis Pasteur
D)  Barbara McClintockE) A) and D)
F) A) and C)

Question 4

How many high-affinity sweet-taste receptors have been identified?

Accepted Answer

A)  none
B)  30
C)  1
D)  10
E)  3F) C) and D)
G) C) and E)

Question 5

Which was NOT an observation made in the initial experiments that revealed effects of auxin signaling?

Accepted Answer

A)  grass seedlings exposed to overhead light bent towards the darkest region of their environment
B)  grass seedlings whose blade tips were removed could not exhibit movement or bending
C)  grass seedlings exposed to laterally-placed light bent towards the light source
D)  grass seedlings tips and bases behaved differently in response to light stimulusE) None of the above
F) A) and B)

Question 6

The enzyme that has been identified as a negative regulator of glycogen synthase is ______.

Accepted Answer

A)  glycogen phosphorylase
B)  glycogen phosphorylase kinase
C)  glycogen synthase kinase-3
D)  insulin synthase kinase
E)  protein kinase AF) C) and E)
G) C) and D)

Question 7

Which of the following features is a requirement for ligand-mediated dimerization?

Accepted Answer

A)  The ligand has only one binding site for receptors.
B)  The ligand has two binding sites for receptors.
C)  The receptor must have a phenylalanine residue in a specific location.
D)  The receptor must have a molecular weight of 50,000 daltons.
E)  Ligand binding causes a conformational shift that reveals a binding site for another receptor.F) B) and D)
G) A) and D)

Question 8

Bcl-2 acts as ________ by promoting ___________.

Accepted Answer

A)  an oncogene, cell division
B)  a haplogene, survival of potential cancer cells that would otherwise die by apoptosis
C)  an oncogene, survival of potential cancer cells that would otherwise die by apoptosis
D)  a cancer gene, survival of potential cancer cells that would otherwise die by apoptosis
E)  a haplogene, cell divisionF) B) and E)
G) A) and E)

Question 9

The _________ pathway of apoptosis is one in which external stimuli activate apoptosis via a signaling pathway.

Accepted Answer

A)  extrinsic
B)  external
C)  intrinsic
D)  peripheral
E)  integralF) C) and D)
G) A) and B)

Question 10

Which gene in C. elegans was found to play a critical role in apoptosis?

Accepted Answer

A)  CED-3
B)  DEG-3
C)  NSO-1
D)  Eco R1
E)  CEL-3F) C) and D)
G) B) and E)

Question 11

Which of the following supports the ligand-mediated model of receptor dimerization?

Accepted Answer

A)  Some growth and differentiation factors like PDGF or CSF-1 are composed of two similar or identical disulfide-linked subunits, each of which has a binding site for a receptor.
B)  Ligands have been found to be proteins that usually dimerize.
C)  Ligands have been found to be steroid hormones.
D)  Ligands were found to bind to each other.
E)  Receptors have been shown to have multiple binding sites for ligands.F) A) and E)
G) C) and D)

Question 12

Following a nerve impulse, what triggers the opening of plasma membrane voltage-gated Ca2+ channels?

Accepted Answer

A)  membrane hyperpolarization
B)  binding of an appropriate ligand
C)  membrane depolarization
D)  membrane hypopolarization
E)  binding of K+ ionsF) A) and E)
G) None of the above

Question 13

In cells exposed to stressful stimuli, like X-rays or damaging chemicals, what response does the MAP kinase cascade coordinate?

Accepted Answer

A)  cell proliferation
B)  withdrawal from the cell cycle
C)  rapid differentiation
D)  slowing of the Krebs cycle
E)  a loss of sensory abilityF) A) and D)
G) B) and D)

Question 14

Once the kinase domain of receptor protein-tyrosine kinase has been activated, what does the activated receptor protein-tyrosine kinase do?

Accepted Answer

A)  The receptor subunits denature.
B)  Each receptor subunit phosphorylates its partner on tyrosine residues found in regions adjacent to the kinase domain.
C)  Each receptor subunit phosphorylates itself on tyrosine residues found in regions adjacent to the kinase domain.
D)  The receptor subunits dephosphorylate each other.
E)  The receptor subunits refold into a more effective conformation.F) B) and D)
G) A) and B)

Question 15

_____ is formed from the amino acid L-______ in a reaction catalyzed by the enzyme _____.

Accepted Answer

A)  Nitrous oxide, arginine, nitrous oxide synthase
B)  Nitric oxide, asparagine, nitric oxide synthase
C)  Nitric oxide, alanine, nitric oxide synthase
D)  Nitric oxide, arginine, nitric oxide synthase
E)  Nitrous oxide, arginine, nitric oxide synthaseF) A) and B)
G) A) and C)

Question 16

Arrestin binding to GPCRs __________.

Accepted Answer

A)  causes the binding of additional G proteins
B)  prevents further activation of additional G proteins
C)  causes denaturation of G proteins
D)  stabilizes G proteins
E)  stabilizes GPCRsF) All of the above
G) B) and C)

Question 17

_________ are enzymes that phosphorylate specific tyrosine residues on protein substrates.

Accepted Answer

A)  Protein tyrosinases
B)  Protein-tyrosine kinases
C)  Tyrosine pronases
D)  Proteokinases
E)  TyrokinasesF) A) and B)
G) None of the above

Question 18

Which hormone is secreted by β-cells in the pancreas in response to low blood glucose levels?

Accepted Answer

A)  insulin
B)  glycogen
C)  glucagon
D)  epinephrine
E)  somatostatinF) All of the above
G) C) and E)

Question 19

Which cells secrete epinephrine?

Accepted Answer

A)  α-cells in the pancreas
B)  β-cells in the pancreas
C)  ɤ-cells in the pancreas
D)  cortical cells in the adrenal gland
E)  medullary cells in the adrenal glandF) A) and E)
G) A) and C)

Question 20

The activation of a common effector by signals from a variety of unrelated receptors, each of which binds to its own ligand, is called _________.

Accepted Answer

A)  divergence
B)  convergence
C)  cross-talk
D)  transvergence
E)  coherenceF) A) and B)
G) A) and C)

Exam 15: Cell Signaling and Signal Transduction: Communication Between Cells

Following a nerve impulse, what triggers the opening of plasma membrane voltage-gated Ca2+ channels?

Correct AnswerverifiedShow Answer

The activation of a common effector by signals from a variety of unrelated receptors, each of which binds to its own ligand, is called _________.

Correct AnswerverifiedShow Answer

Which of the following features is a requirement for ligand-mediated dimerization?

Correct AnswerverifiedShow Answer

The enzyme that has been identified as a negative regulator of glycogen synthase is ______.

Correct AnswerverifiedShow Answer

Which hormone is secreted by β-cells in the pancreas in response to low blood glucose levels?

Correct AnswerverifiedShow Answer

The _________ pathway of apoptosis is one in which external stimuli activate apoptosis via a signaling pathway.

Correct AnswerverifiedShow Answer

Which was NOT an observation made in the initial experiments that revealed effects of auxin signaling?

Correct AnswerverifiedShow Answer

Once the kinase domain of receptor protein-tyrosine kinase has been activated, what does the activated receptor protein-tyrosine kinase do?

Correct AnswerverifiedShow Answer

The auxin response factor (ARF) family members are believed to encode _______________.

Correct AnswerverifiedShow Answer

Which gene in C. elegans was found to play a critical role in apoptosis?

Correct AnswerverifiedShow Answer

Who was one of the first scientists to observe the effects of the plant hormone auxin?

Correct AnswerverifiedShow Answer

Arrestin binding to GPCRs __________.

Correct AnswerverifiedShow Answer

_________ are enzymes that phosphorylate specific tyrosine residues on protein substrates.

Correct AnswerverifiedShow Answer

_____ is formed from the amino acid L-______ in a reaction catalyzed by the enzyme _____.

Correct AnswerverifiedShow Answer

Which of the following supports the ligand-mediated model of receptor dimerization?

Correct AnswerverifiedShow Answer

Which amino acids are known to be phosphorylated by protein kinases?

Correct AnswerverifiedShow Answer

In cells exposed to stressful stimuli, like X-rays or damaging chemicals, what response does the MAP kinase cascade coordinate?

Correct AnswerverifiedShow Answer

How many high-affinity sweet-taste receptors have been identified?

Correct AnswerverifiedShow Answer

Which cells secrete epinephrine?

Correct AnswerverifiedShow Answer

Bcl-2 acts as ________ by promoting ___________.

Correct AnswerverifiedShow Answer

Following a nerve impulse, what triggers the opening of plasma membrane voltage-gated Ca²⁺ channels?

Correct Answer
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_ is formed from the amino acid L- in a reaction catalyzed by the enzyme ___.

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Bcl-2 acts as by promoting ___.

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