CH 461 Lecture Notes - Lecture 29: Adenylyl Cyclase, Cyclic Adenosine Monophosphate, Glycogen Phosphorylase
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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 |
Part A
The ultimate problem with cholera that can lead to death is __________.
The ultimate problem with cholera that can lead to death is __________.
| only water loss |
| fluid loss with electrolyte concentrations remaining normal |
| severe dehydration and electrolyte imbalance |
| only electrolyte loss |
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Part B
The loss of chloride ions is occurring as a result of an continuously open __________, found in certain intestinal epithelial cells.
The loss of chloride ions is occurring as a result of an continuously open __________, found in certain intestinal epithelial cells.
| chloride channel protein |
| sodium pump |
| ATP dependent sodium/potassium pump |
| potassium pump |
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Part C
The main purpose of the chloride channel proteins on the apical surface of the intestinal epithelial cells is to create an osmotic gradient that ultimately causes __________ to move through the intestinal epithelium and into the intestinal lumen to assist in the formation of mucus. These are the same chloride channel proteins, adversely affected in cystic fibrosis.
The main purpose of the chloride channel proteins on the apical surface of the intestinal epithelial cells is to create an osmotic gradient that ultimately causes __________ to move through the intestinal epithelium and into the intestinal lumen to assist in the formation of mucus. These are the same chloride channel proteins, adversely affected in cystic fibrosis.
| potassium |
| calcium |
| water |
| sodium |
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Part D
The main physiologic mechanism used to control the opening of the chloride channel protein is through the use of __________.
The main physiologic mechanism used to control the opening of the chloride channel protein is through the use of __________.
| G proteinâlinked receptors |
| potassium pump |
| enzyme-linked receptors |
| sodium pump |
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Part E
The main factor that causes cholera is the overstimulation of __________ by the __________.
The main factor that causes cholera is the overstimulation of __________ by the __________.
| guanylate cyclase; the bacterium Vibrio cholerae |
| adenylate cyclase; the bacterium Vibrio cholerae |
| guanylate cyclase; cholera toxin |
| adenylate cyclase; cholera toxin |
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Part F
The normal physiologic mechanism used by G proteinâlinked receptors is for a ligand to bind to the G proteinâlinked receptor; this in turn activates __________ located in the intracellular side of the plasma membrane, which eventually leads to the physiologic effector action.
The normal physiologic mechanism used by G proteinâlinked receptors is for a ligand to bind to the G proteinâlinked receptor; this in turn activates __________ located in the intracellular side of the plasma membrane, which eventually leads to the physiologic effector action.
| diacylglycerol |
| inositol triphosphate |
| G protein |
| cyclic AMP |
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Part G
Cholera toxin bypasses the normal sequential cascade of events involving G protein activation. The __________subunit of cholera toxin enters into the cell and directly activates __________. This leads to a non-physiologic (non-homeostatic) action of inappropriately maintaining the chloride channel proteins open. This causes excessive __________, sodium, and water to leave the intestinal epithelial cells.
Cholera toxin bypasses the normal sequential cascade of events involving G protein activation. The __________subunit of cholera toxin enters into the cell and directly activates __________. This leads to a non-physiologic (non-homeostatic) action of inappropriately maintaining the chloride channel proteins open. This causes excessive __________, sodium, and water to leave the intestinal epithelial cells.
| A; G protein; chloride |
| B; G protein; chloride |
| B; inositol triphosphate; calcium |
| A; diacylglycerol; chloride |
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Part H
A defect in the chloride channel protein, causing it to not open, will _________ the chloride, sodium, and water loss in cholera. However, it will also cause the individual to have __________ mucus.
A defect in the chloride channel protein, causing it to not open, will _________ the chloride, sodium, and water loss in cholera. However, it will also cause the individual to have __________ mucus.
| allow; thick |
| allow; thin |
| prevent, thin |
| prevent; thick |
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Part I
A drug that prevents the cholera toxin from attaching to the __________ in the intestinal epithelial cell could be a useful treatment.
A drug that prevents the cholera toxin from attaching to the __________ in the intestinal epithelial cell could be a useful treatment.
| ganglioside |
| protein |
| phospholipid |
| AMP |
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Part J
The best method to reduce the spread of cholera is to __________.
The best method to reduce the spread of cholera is to __________.
| never travel to underdeveloped countries |
| provide properly treated water supplies |
| give everyone antibiotics |
| give everyone antacids |