Question 1

Addison's disease is a disorder that results from a reduction in production of glucocorticoids and mineralocorticoids.Individuals with Addison's disease suffer from a variety of systemic symptoms including: muscle weakness,fever,issues with the gastrointestinal tract,and increased tanning.Considering this information,what type of signaling do you think that glucocorticoids and mineralocorticoids stimulate?

Accepted Answer

A)  Direct contact
B)  Paracrine
C)  Endocrine
D)  Synaptic
E)  AutocrineF) C) and E)
G) C) and D)

Question 2

Leptin is a circulating hormone that is produced by fat cells and plays a role in body metabolism and obesity.It normally binds to receptors in the brain and inhibits appetite.Studies have demonstrated that when obese mice that are leptin deficient are injected with leptin they quickly lose their excess weight.Interestingly,however,many overweight people have high levels of leptin in their bloodstream.Why do you think that the high levels of leptin in obese individuals are insufficient to curb their appetite?

Accepted Answer

A)  Paracrine signaling may be disrupted in obese people with high levels of leptin.
B)  Obese people who have high levels of leptin may have a leptin receptor with decreased sensitivity.
C)  The form of leptin released by obese people may lack protein kinase activity.
D)  In obese people with high levels of leptin,the leptin is a non-functional second messenger.E) C) and D)
F) None of the above

Question 3

Ste5 binds to MAPKKK,MAPKK,and MAPK to organize the kinase cascade.What type of signaling molecule is Ste5?

Accepted Answer

A)  Scaffold
B)  Adapter protein
C)  Second messenger
D)  EnzymeE) B) and D)
F) None of the above

Question 4

A mutation that affects Ca++ binding to calmodulin is most likely to interfere with what aspect of a signal transduction pathway?

Accepted Answer

A)  The flow of Ca++ ions through ion channel receptors
B)  The cellular response to the second messenger
C)  The MAP kinase cascade
D)  G protein activityE) B) and C)
F) A) and D)

Question 5

G protein-coupled receptors are the largest family of cell surface receptors.Each receptor passes through the plasma membrane how many times?

Accepted Answer

A)  Once
B)  Three times
C)  Five times
D)  Seven timesE) A) and D)
F) A) and C) D

Question 6

What is similar about G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs) ?

Accepted Answer

A)  Both are directly bound to G proteins
B)  Both can activate phospholipase C
C)  Both are enzymes
D)  Both are activated by autophosphorylationE) A) and B)
F) B) and D)

Question 7

What is the function of a protein kinase?

Accepted Answer

A)  To remove phosphate groups from proteins
B)  To cleave membrane phospholipids
C)  To phosphorylate GDP to generate GTP
D)  To add phosphate groups onto proteinsE) A) and D)
F) All of the above

Question 8

How are receptor tyrosine kinases and steroid hormone receptors similar?

Accepted Answer

A)  Both are activated by autophosphorylation
B)  Both are transmembrane proteins with a single transmembrane domain
C)  Both have a DNA-binding domain
D)  Both have a site for binding ligandE) None of the above
F) B) and C)

Question 9

A researcher is working to generate a new cancer drug.Thus far,he has identified a compound that can reduce the size of tumors in the lung.However,in order for the drug to work,the lung tumor has to be small.In addition,the tumor cannot have metastasized (spread to other areas of the body) .Furthermore,he knows that the drug acts to prohibit the signaling from one tumor cell to another tumor cell.Given the above information,this new drug prohibits:

Accepted Answer

A)  synaptic signaling between tumor cells.
B)  autocrine signaling between tumor cells.
C)  paracrine signaling between tumor cells.
D)  endocrine signaling between tumor cells.E) All of the above
F) A) and D) C

Question 10

In the nitric oxide signaling pathway,nitric oxide activates an enzyme that can convert many molecules of GTP into molecules of cGMP.cGMP is a small molecule that can diffuse through the cytoplasm and bind to an enzyme called protein kinase G (PKG) .Binding of cGMP to PKG leads to a change in the confirmation of PKG that leads to its activation.What type of signaling molecule is cGMP?

Accepted Answer

A)  Scaffold
B)  Adapter protein
C)  Second messenger
D)  EnzymeE) C) and D)
F) A) and C)

Question 11

What signaling pathway commonly makes use of a G protein to transduce the signal?

Accepted Answer

A)  Channel-linked receptor pathways
B)  Steroid hormone receptor pathways
C)  Receptor tyrosine kinase pathwaysD) A) and B)
E) None of the above

Question 12

Using a specific chemical,a cell biologist has blocked one type of channel-linked receptor in a lab rat's liver tissue.What was the likely mechanism of the chemical she used?

Accepted Answer

A)  The chemical prohibits binding of a ligand to the receptor.
B)  The chemical prohibits ions from entering the cell via active transport.
C)  The chemical causes ions to move in the opposite direction of the ion gradient.
D)  The chemical prohibits second messenger signaling.E) None of the above
F) B) and C)

Question 13

A mutation in the DNA-binding domain of a steroid hormone receptor is most likely to affect what aspect of receptor function?

Accepted Answer

A)  The conformational change of the receptor
B)  The binding of the hormone to the receptor
C)  The translocation of the receptor to the nucleus
D)  The cellular response to the hormoneE) B) and D)
F) None of the above

Question 14

Many receptor tyrosine kinase (RTK) pathways lead to the activation of Ras.To activate Ras,it is necessary to recruit a guanine nucleotide exchange factor to the plasma membrane,because Ras is a membrane associated protein.Guanine nucleotide exchange factors,such as SOS,stimulate the exchange of GDP for GTP.However,SOS cannot bind directly to most RTKs.The protein Grb2 has a domain that can bind to phosphorylated tyrosines,and another domain that can bind to SOS.Therefore,Grb2 can bind to active RTKs and recruit SOS to the plasma membrane.Grb2 is an example of what kind of signaling molecule?

Accepted Answer

A)  Scaffold
B)  Adapter protein
C)  Second messenger
D)  EnzymeE) A) and B)
F) A) and C)

Question 15

In response to injury,cell fragments called platelets get activated to induce clotting.Activated platelets release factors that can in turn bind to specific membrane receptors on nearby cells.What type of signaling would this be considered?

Accepted Answer

A)  Direct contact
B)  Paracrine
C)  Endocrine
D)  Synaptic
E)  AutocrineF) D) and E)
G) C) and E)

Question 16

These molecules can directly convert extracellular signals into intracellular signals.

Accepted Answer

A)  Second messengers
B)  Scaffolds
C)  Membrane receptors
D)  Adapter proteins
E)  G proteinsF) B) and C)
G) A) and E)

Question 17

You are interested in developing an inhibitor for the estrogen receptor.You have identified a molecule that is small and hydrophilic.In a test tube,this inhibitor binds tightly to the estrogen receptor,and inhibits the interaction of the receptor with estrogen.Do you think that this molecule will be an effective inhibitor of the estrogen receptor in cells?

Accepted Answer

A)  Yes,because it can prevent estrogen binding.
B)  Yes,because it is small.
C)  No,because it is hydrophilic.
D)  No,because it will need to bind to the DNA-binding domain to act as an inhibitor.E) A) and C)
F) A) and B)

Question 18

If the effector protein phospholipase C failed to cleave phosphatidylinositol-4,5-bisphosphate (PIP2) ,the action of what enzyme would be affected?

Accepted Answer

A)  cAMP
B)  IP3
C)  protein kinase A (PK
A)  
D)  protein kinase C (PK
C)  E) A) and D)
F) A) and B)

Question 19

Some cancers are caused by the overexpression of receptor tyrosine kinases (RTKs) .It is known that RTK signaling pathways commonly stimulate cell division.Why would the overexpression of receptor tyrosine kinases lead to cancer development?

Accepted Answer

A)  RTKs are activated by dimerization,caused by ligand binding.If there are too many receptors on the cell surface,it is possible that these receptors dimerize in the absence of ligand binding,thus stimulating cell division at inappropriate times.
B)  If there are too many RTKs on the cell surface,this will tend to allow cells to adhere to each other.Once they adhere,RTKs from one cell can bind to RTKs from another cell,and they can activate each other leading to activation of downstream signaling pathways in both cells.
C)  If there are too many RTKs on the cell surface,it is less likely that inhibitors will bind to all of the available RTKs and block their ability to enter the nucleus.As a result,some of the RTKs will be able to enter the nucleus to stimulate transcription.
D)  If there are too many RTKs on the cell surface,this will promote the inhibition of autophosphorylation.In the absence of autophosphorylation,it is more likely that the RTK downstream signaling pathway will be active.E) None of the above
F) C) and D)

Question 20

What is the mechanism by which binding of testosterone to the testosterone receptor leads to upregulated gene transcription?

Accepted Answer

A)  Binding of testosterone to the testosterone receptor leads to the increase in second messengers that activate a kinase cascade,ultimately leading to the activation of transcription factors that promote gene transcription.
B)  Binding of testosterone to the testosterone receptor leads to the activation of a G protein that stimulates the activation of enzymes that promote gene transcription.
C)  Binding of testosterone to the testosterone receptor leads to a conformational change that allows the receptor to enter the nucleus where it can bind to DNA and promote gene transcription.
D)  Binding of testosterone to the testosterone receptor leads to the opening of an ion channel that leads to an increase in calcium in the cytoplasm.The increased calcium levels activate calmodulin,which can go on to activate other proteins that promote gene transcription.E) A) and B)
F) B) and D) C

Exam 9: Cell Communication

Correct Answer
verified

Correct Answer
verified

Ste5 binds to MAPKKK,MAPKK,and MAPK to organize the kinase cascade.What type of signaling molecule is Ste5?

Correct Answer
verified

A mutation that affects Ca⁺⁺ binding to calmodulin is most likely to interfere with what aspect of a signal transduction pathway?

Correct Answer
verified

G protein-coupled receptors are the largest family of cell surface receptors.Each receptor passes through the plasma membrane how many times?

Correct Answer
verified
D

What is similar about G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs) ?

Correct Answer
verified

What is the function of a protein kinase?

Correct Answer
verified

How are receptor tyrosine kinases and steroid hormone receptors similar?

Correct Answer
verified

Correct Answer
verified
C

Correct Answer
verified

What signaling pathway commonly makes use of a G protein to transduce the signal?

Correct Answer
verified

Using a specific chemical,a cell biologist has blocked one type of channel-linked receptor in a lab rat's liver tissue.What was the likely mechanism of the chemical she used?

Correct Answer
verified

A mutation in the DNA-binding domain of a steroid hormone receptor is most likely to affect what aspect of receptor function?

Correct Answer
verified

Correct Answer
verified

In response to injury,cell fragments called platelets get activated to induce clotting.Activated platelets release factors that can in turn bind to specific membrane receptors on nearby cells.What type of signaling would this be considered?

Correct Answer
verified

These molecules can directly convert extracellular signals into intracellular signals.

Correct Answer
verified

Correct Answer
verified

If the effector protein phospholipase C failed to cleave phosphatidylinositol-4,5-bisphosphate (PIP₂) ,the action of what enzyme would be affected?

Correct Answer
verified

Some cancers are caused by the overexpression of receptor tyrosine kinases (RTKs) .It is known that RTK signaling pathways commonly stimulate cell division.Why would the overexpression of receptor tyrosine kinases lead to cancer development?

Correct Answer
verified

What is the mechanism by which binding of testosterone to the testosterone receptor leads to upregulated gene transcription?

Correct Answer
verified
C

Exam 9: Cell Communication

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Ste5 binds to MAPKKK,MAPKK,and MAPK to organize the kinase cascade.What type of signaling molecule is Ste5?

Correct AnswerverifiedShow Answer

A mutation that affects Ca++ binding to calmodulin is most likely to interfere with what aspect of a signal transduction pathway?

Correct AnswerverifiedShow Answer

G protein-coupled receptors are the largest family of cell surface receptors.Each receptor passes through the plasma membrane how many times?

Correct AnswerverifiedD

What is similar about G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs) ?

Correct AnswerverifiedShow Answer

What is the function of a protein kinase?

Correct AnswerverifiedShow Answer

How are receptor tyrosine kinases and steroid hormone receptors similar?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedC

Correct AnswerverifiedShow Answer

What signaling pathway commonly makes use of a G protein to transduce the signal?

Correct AnswerverifiedShow Answer

Using a specific chemical,a cell biologist has blocked one type of channel-linked receptor in a lab rat's liver tissue.What was the likely mechanism of the chemical she used?

Correct AnswerverifiedShow Answer

A mutation in the DNA-binding domain of a steroid hormone receptor is most likely to affect what aspect of receptor function?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

In response to injury,cell fragments called platelets get activated to induce clotting.Activated platelets release factors that can in turn bind to specific membrane receptors on nearby cells.What type of signaling would this be considered?

Correct AnswerverifiedShow Answer

These molecules can directly convert extracellular signals into intracellular signals.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

If the effector protein phospholipase C failed to cleave phosphatidylinositol-4,5-bisphosphate (PIP2) ,the action of what enzyme would be affected?

Correct AnswerverifiedShow Answer

Some cancers are caused by the overexpression of receptor tyrosine kinases (RTKs) .It is known that RTK signaling pathways commonly stimulate cell division.Why would the overexpression of receptor tyrosine kinases lead to cancer development?

Correct AnswerverifiedShow Answer

What is the mechanism by which binding of testosterone to the testosterone receptor leads to upregulated gene transcription?

Correct AnswerverifiedC

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

A mutation that affects Ca⁺⁺ binding to calmodulin is most likely to interfere with what aspect of a signal transduction pathway?

Correct Answer
verified

Correct Answer
verified
D

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
C

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

If the effector protein phospholipase C failed to cleave phosphatidylinositol-4,5-bisphosphate (PIP₂) ,the action of what enzyme would be affected?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
C