QUESTION 1
Many mutations in receptor kinases that lead to cancer allow the dimerization and activation of the receptor, even in the absence of signaling molecule. An example of this is a mutant form of the EGF receptor kinase called Her2/neu. An antibody that prevents dimerization of Her2/neu receptor kinases is being tested for its effectiveness in stopping cancer. At which stage would this drug work?
A.
It would prevent the signaling cell from producing the signal.
B.
It would prevent the receptor from binding to the signal.
C.
It would prevent the receptor from becoming activated.
D.
It would prevent the termination of the signal.
1 points
QUESTION 2
Which type of cell signaling does not rely on the diffusion of a chemical signal
molecule?
A.
juxtacrine
B.
paracrine
C.
autocrine
D.
endocrine
E.
All of these choices are correct.
1 points
QUESTION 3
Steroid hormones:
A.
have the same effect on different types of cells.
B.
bind to cell-surface receptors.
C.
bind intracellular receptors to form complexes that migrate to the nucleus.
D.
facilitate the initiation of translation by ribosomes.
1 points
QUESTION 4
Which type of signal receptor dimerizes upon ligand binding, leading to phosphorylation of the receptor dimer?
A.
G protein-coupled receptor
B.
receptor tyrosine kinase
C.
ligand-gated ion channel
D.
nuclear receptor
1 points
QUESTION 5
Which of the following is a part of the MAP kinase pathway?
A.
A receptor kinase is activated by binding to a growth factor and phosphorylates receptor cytoplasmic domains.
B.
phosphorylated sites on the receptor dimer recruit a signaling complex that stimulates Ras to release GDP and bind GTP
C.
The activated RAS protein activates a protein kinase in the signal-transduction pathway.
D.
A series of protein kinases amplify the signal to the nucleus where a transcription factor causes increased transcription of genes involved in the cell division cycle
E.
all of the above
1 points
QUESTION 6
An increased heart rate caused by the release of epinephrine from the adrenal glands and movement of the epinephrine through the blood stream to the heart is an example of _______________________________.
A.
autocrine signaling
B.
juxtacrine signaling
C.
paracrine signaling
D.
endocrine signaling
1 points
QUESTION 7
At the neuromuscular junction, acetylcholine released from a motor neuron
A.
binds to and opens Na+ channels on skeletal muscle cells
B.
causes an action potential in the motor neuron
C.
causes hyperpolarization of skeletal muscle cells
1 points
QUESTION 8
A mutated ras allele encodes Ras protein that is unable to hydrolyze GTP to GDP. What does this do?
A.
keeps Ras permanently active
B.
prevents Ras activity
C.
Neither
1 points
QUESTION 9
Phosphatases are a family of enzymes that specifically remove phosphate groups from proteins that were added by protein kinases. Vanadate is an inhibitor of tyrosine phosphatases in eukaryotic cells. What effect would vanadate have on the response of cells to signals received by receptor tyrosine kinases?
A.
The response of the cell would last longer than it normally would.
B.
The response of the cell would be shorter than it normally would.
C.
The signal would still bind the receptor, so there would be no effect.
1 points
QUESTION 10
A cellular response to a signal can be terminated by:
A.
disassociation of the ligand from the receptor.
B.
inactivation of intracellular signal transduction proteins.
C.
endocytosis of the receptor
D.
depletion of a second messenger.
E.
All of these choices are correct.
1 points
QUESTION 11
The type of cellular response to a signal depends on:
A.
the type of receptor being expressed in the cell.
B.
the type of intracellular signal transduction proteins being expressed in the cell.
C.
other signals to which the cell is concurrently responding.
D.
All of these choices are correct.
1 points
QUESTION 12
Cell-to-cell signaling involves
A.
a ligand
B.
a signaling cell
C.
a receptor
D.
a responding cell
E.
all of the above
1 points
QUESTION 13
An important signaling event that determines whether or not a cell will become a neuron involves binding of a transmembrane protein in one cell directly to a transmembrane protein of another cells, initiating intracellular signaling in one of the cells. This is an example of ___________ signaling.
A.
juxtacrine
B.
paracrine
C.
autocrine
D.
endocrine
E.
All of these choices are correct.
1 points
QUESTION 14
Which type of receptor is an intracellular receptor (i.e. not an integral plasma membrane protein)?
A.
G protein-coupled receptor
B.
receptor tyrosine kinase
C.
ligand-gated ion channel
D.
nuclear receptor
1 points
QUESTION 15
After acetylcholine is secreted by a motor neuron and stimulates initiation of an action potential in skeletal muscle, the signal is reversed by:
A.
depletion of acetylcholine, which returns the ligand-gated ion channel to the resting, closed conformation, preventing further transport of sodium ions.
B.
an ATP-powered sodium pump in the plasma membrane that continuously works to set up a sodium concentration gradient.
C.
an enzyme that degrades and removes acetylcholine from the neuromuscular junction.
D.
a resting neuron that stops releasing acetylcholine into the neuromuscular junction.
E.
All of these choices are correct.
1 points
QUESTION 16
Which of the following scenarios would result in a proliferation signal via the MAP kinase cascade in the absence of ligand binding to its receptor tyrosine kinase?
A.
a continuously active MAP kinase kinase
B.
a Ras molecule that has no GTPase activity
C.
a continuously inactive MAP kinase pathway and an inactive Ras
D.
prevention of activity of phosphatases that would normally dephosphorylate kinases in the MAPK cascade or the transcription factors phosphorylated by MAPK
E.
all of the above
1 points
QUESTION 17
Which of these is NOT a protein?
A.
receptor tyrosine kinase
B.
Ras
C.
transcription factor
D.
cAMP
E.
ligand gated ion channel
1 points
QUESTION 18
Ras is a cytosolic protein. Where is the mRNA for Ras translated?
A.
a ribosome in the cytosol
B.
a ribosome in the cytosol that has been directed to the surface of the rough ER
C.
nucleus
1 points
QUESTION 19
Activation of MAPK leads to phosphorylation of transcription factors. What is a DIRECT (i.e. occurring before any of the others on the list) result of this?
A.
change in rates of transcription of specific genes involved in regulation of the cell cycle
B.
increased synthesis of proteins
C.
cell division
1 points
QUESTION 20
A GPCR is a plasma membrane protein. Where is the mRNA for this GPCR translated?
A.
a ribosome in the cytosol
B.
a ribosome in the cytosol that has been directed to the surface of the rough ER
C.
nucleus
1 points
QUESTION 21
What is the monomer that is polymerized to synthesize a GPCR protein?
A.
epinephrine
B.
amino acid
C.
ribonucleotide
D.
deoxyribonucleotide
E.
monosaccharide
1 points
QUESTION 22
What is the monomer that is polymerized to form the mRNA for a GPCR?
A.
epinephrine
B.
amino acid
C.
ribonucleotide
D.
deoxyribonucleotide
E.
monosaccharide
1 points
QUESTION 23
The gene for a GPCR is a segment of a polymer composed of which monomer?
A.
epinephrine
B.
amino acid
C.
ribonucleotide
D.
deoxyribonucleotide
E.
monosaccharide
QUESTION 1
Many mutations in receptor kinases that lead to cancer allow the dimerization and activation of the receptor, even in the absence of signaling molecule. An example of this is a mutant form of the EGF receptor kinase called Her2/neu. An antibody that prevents dimerization of Her2/neu receptor kinases is being tested for its effectiveness in stopping cancer. At which stage would this drug work?
A.
It would prevent the signaling cell from producing the signal.
B.
It would prevent the receptor from binding to the signal.
C.
It would prevent the receptor from becoming activated.
D.
It would prevent the termination of the signal.
1 points
QUESTION 2
Which type of cell signaling does not rely on the diffusion of a chemical signal
molecule?
A.
juxtacrine
B.
paracrine
C.
autocrine
D.
endocrine
E.
All of these choices are correct.
1 points
QUESTION 3
Steroid hormones:
A.
have the same effect on different types of cells.
B.
bind to cell-surface receptors.
C.
bind intracellular receptors to form complexes that migrate to the nucleus.
D.
facilitate the initiation of translation by ribosomes.
1 points
QUESTION 4
Which type of signal receptor dimerizes upon ligand binding, leading to phosphorylation of the receptor dimer?
A.
G protein-coupled receptor
B.
receptor tyrosine kinase
C.
ligand-gated ion channel
D.
nuclear receptor
1 points
QUESTION 5
Which of the following is a part of the MAP kinase pathway?
A.
A receptor kinase is activated by binding to a growth factor and phosphorylates receptor cytoplasmic domains.
B.
phosphorylated sites on the receptor dimer recruit a signaling complex that stimulates Ras to release GDP and bind GTP
C.
The activated RAS protein activates a protein kinase in the signal-transduction pathway.
D.
A series of protein kinases amplify the signal to the nucleus where a transcription factor causes increased transcription of genes involved in the cell division cycle
E.
all of the above
1 points
QUESTION 6
An increased heart rate caused by the release of epinephrine from the adrenal glands and movement of the epinephrine through the blood stream to the heart is an example of _______________________________.
A.
autocrine signaling
B.
juxtacrine signaling
C.
paracrine signaling
D.
endocrine signaling
1 points
QUESTION 7
At the neuromuscular junction, acetylcholine released from a motor neuron
A.
binds to and opens Na+ channels on skeletal muscle cells
B.
causes an action potential in the motor neuron
C.
causes hyperpolarization of skeletal muscle cells
1 points
QUESTION 8
A mutated ras allele encodes Ras protein that is unable to hydrolyze GTP to GDP. What does this do?
A.
keeps Ras permanently active
B.
prevents Ras activity
C.
Neither
1 points
QUESTION 9
Phosphatases are a family of enzymes that specifically remove phosphate groups from proteins that were added by protein kinases. Vanadate is an inhibitor of tyrosine phosphatases in eukaryotic cells. What effect would vanadate have on the response of cells to signals received by receptor tyrosine kinases?
A.
The response of the cell would last longer than it normally would.
B.
The response of the cell would be shorter than it normally would.
C.
The signal would still bind the receptor, so there would be no effect.
1 points
QUESTION 10
A cellular response to a signal can be terminated by:
A.
disassociation of the ligand from the receptor.
B.
inactivation of intracellular signal transduction proteins.
C.
endocytosis of the receptor
D.
depletion of a second messenger.
E.
All of these choices are correct.
1 points
QUESTION 11
The type of cellular response to a signal depends on:
A.
the type of receptor being expressed in the cell.
B.
the type of intracellular signal transduction proteins being expressed in the cell.
C.
other signals to which the cell is concurrently responding.
D.
All of these choices are correct.
1 points
QUESTION 12
Cell-to-cell signaling involves
A.
a ligand
B.
a signaling cell
C.
a receptor
D.
a responding cell
E.
all of the above
1 points
QUESTION 13
An important signaling event that determines whether or not a cell will become a neuron involves binding of a transmembrane protein in one cell directly to a transmembrane protein of another cells, initiating intracellular signaling in one of the cells. This is an example of ___________ signaling.
A.
juxtacrine
B.
paracrine
C.
autocrine
D.
endocrine
E.
All of these choices are correct.
1 points
QUESTION 14
Which type of receptor is an intracellular receptor (i.e. not an integral plasma membrane protein)?
A.
G protein-coupled receptor
B.
receptor tyrosine kinase
C.
ligand-gated ion channel
D.
nuclear receptor
1 points
QUESTION 15
After acetylcholine is secreted by a motor neuron and stimulates initiation of an action potential in skeletal muscle, the signal is reversed by:
A.
depletion of acetylcholine, which returns the ligand-gated ion channel to the resting, closed conformation, preventing further transport of sodium ions.
B.
an ATP-powered sodium pump in the plasma membrane that continuously works to set up a sodium concentration gradient.
C.
an enzyme that degrades and removes acetylcholine from the neuromuscular junction.
D.
a resting neuron that stops releasing acetylcholine into the neuromuscular junction.
E.
All of these choices are correct.
1 points
QUESTION 16
Which of the following scenarios would result in a proliferation signal via the MAP kinase cascade in the absence of ligand binding to its receptor tyrosine kinase?
A.
a continuously active MAP kinase kinase
B.
a Ras molecule that has no GTPase activity
C.
a continuously inactive MAP kinase pathway and an inactive Ras
D.
prevention of activity of phosphatases that would normally dephosphorylate kinases in the MAPK cascade or the transcription factors phosphorylated by MAPK
E.
all of the above
1 points
QUESTION 17
Which of these is NOT a protein?
A.
receptor tyrosine kinase
B.
Ras
C.
transcription factor
D.
cAMP
E.
ligand gated ion channel
1 points
QUESTION 18
Ras is a cytosolic protein. Where is the mRNA for Ras translated?
A.
a ribosome in the cytosol
B.
a ribosome in the cytosol that has been directed to the surface of the rough ER
C.
nucleus
1 points
QUESTION 19
Activation of MAPK leads to phosphorylation of transcription factors. What is a DIRECT (i.e. occurring before any of the others on the list) result of this?
A.
change in rates of transcription of specific genes involved in regulation of the cell cycle
B.
increased synthesis of proteins
C.
cell division
1 points
QUESTION 20
A GPCR is a plasma membrane protein. Where is the mRNA for this GPCR translated?
A.
a ribosome in the cytosol
B.
a ribosome in the cytosol that has been directed to the surface of the rough ER
C.
nucleus
1 points
QUESTION 21
What is the monomer that is polymerized to synthesize a GPCR protein?
A.
epinephrine
B.
amino acid
C.
ribonucleotide
D.
deoxyribonucleotide
E.
monosaccharide
1 points
QUESTION 22
What is the monomer that is polymerized to form the mRNA for a GPCR?
A.
epinephrine
B.
amino acid
C.
ribonucleotide
D.
deoxyribonucleotide
E.
monosaccharide
1 points
QUESTION 23
The gene for a GPCR is a segment of a polymer composed of which monomer?
A.
epinephrine
B.
amino acid
C.
ribonucleotide
D.
deoxyribonucleotide
E.
monosaccharide
Unlock all answers
Related textbook solutions
Related questions
QUESTION 1
Which of the following is an example of an extracellular signal molecule?
| a. | IP3 | |
| b. | cAMP | |
| c. | Insulin | |
| d. | Diacylglycerol |
2 points
QUESTION 2
Nuclear hormone receptors _____
| a. | Bind to water soluble ligands | |
| b. | Activate second messengers | |
| c. | Regulate transcription in response to ligand binding | |
| d. | Are normally located on the plasma membrane |
2 points
QUESTION 3
Which of the following does not occur when a receptor tyrosine kinase is bound by ligand?
| a. | Phosphorylation of the RTK | |
| b. | Cytoplasmic proteins bind the phosphorylated RTK | |
| c. | Dimerization of the RTK | |
| d. | The RTK binds to DNA to regulate transcription |
2 points
QUESTION 4
Which of these is a logical signal-transduction pathway?
| a. | An intracellular receptor activates phospholipase C, which cleaves a membrane protein to form IP3, which then activates the opening of an ER channel protein, which releases cyclic AMP into the cytoplasm, where it binds to an intracellular enzyme that carries out a response. | |
| b. | A G-protein-linked receptor activates G protein, which activates phospholipase C, which cleaves a membrane lipid to form IP3, which binds to a calcium channel on the ER, which opens to release calcium ions into the cytoplasm, which bind to an intracellular enzyme that carries out a response. | |
| c. | An ion-channel receptor opens, allowing a steroid hormone to enter the cell; the steroid hormone then activates protein kinases that convert GTP to GDP, which binds to an intracellular enzyme that carries out a response. | |
| d. | A tyrosine-kinase receptor activates adenylyl cyclase, which activates phospholipase C, which converts ATP into cyclic AMP, which binds to an intracellular enzyme that carries out a response. |
2 points
QUESTION 5
Which of the following is an example of signal amplification?
| a. | activation of an enzyme molecule | |
| b. | activation of a specific gene by a growth factor | |
| c. | Breakdown of many cAMP molecules | |
| d. | activation of 100 molecules by a single signal binding event |
2 points
QUESTION 6
Consider a signal transduction pathway that utilizes cAMP as a second messenger to activate PKA (Protein Kinase A). Which of the following situations will result in the cellular response?
| The G protein releases GDP and binds to GTP | ||
| The target protein (adenylyl cyclase) is inactive | ||
| The regulatory subunits of PKA (Protein Kinase A) are bound to the catalytic subunits | ||
| The appropriate G protein is bound to GDP |
2 points
QUESTION 7
Which of the following is found in only some signal transduction pathways? [In other words, which is not found in all signal transduction pathways?]
| Receptor protein | ||
| Extracellular signal molecule | ||
| Intracellular signaling molecule | ||
| Cellular response | ||
| Effector protein |
2 points
QUESTION 8
The enzyme that specifically catalyzes the conversion of ATP to cAMP is:
| Adenylyl phosphatase | ||
| Adenylyl kinase | ||
| Adenylyl dehydrogenase | ||
| Adenylyl cyclase |
2 points
QUESTION 9
If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?
| It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. | ||
| It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. | ||
| It would employ a transduction pathway directly from an external messenger. | ||
| It would be able to carry out reception and transduction but would not be able to respond to a signal. |
2 points
QUESTION 10
A hormone signal is sent from the brain to other parts of the body via the bloodstream. Why do only certain cells respond to this signal?
| Hormones do not last long enough in the bloodstream to stimulate a cellular response | ||
| Only cells that have a specific transcription factor gene will be able to respond to the signal | ||
| Only cells in the immediate vicinity of the cell sending the signal will respond | ||
| Only cells that have a receptor for the specific signal will be able to respond to it |
