Questions:

1. Following the release of all chemical messengers from their source cells, all of the following will occur EXCEPT
  1. The hormone will travel to its target cell
  2. The hormone will enter its target cell
  3. The hormone the bind specifically to its receptor
  4. The hormone elicits a response
  5. The hormone response eventually ceases
2. When a hormone binds to a specific receptor on the cell membrane, all of the following might occur EXCEPT
  1. The initiation of a covalent bond between the receptor and the hormone
  2. The initiation of a specific signal transduction pathway
  3. The inhibition of control enzymes controlling certain pathways
  4. The activation of control enzymes controlling certain pathways
  5. The activation or repression of transcription factors
3. On a motor neuron, when an action potential travels to the neuromuscular junction all of the following might be expected EXCEPT
  1. Voltage gated calcium channels open and calcium floods into the nerve cell
  2. Vesicales containing acetylcholine fuse with the presynaptic membrane
  3. The neurotransmitter acetylcholine is released into the synapse
  4. The acetylcholine binds to acetylcholine esterase and depolarizes the muscle cell
  5. Depolarization of the muscle cell starts a new action potential
4. A chemical messenger (hormone) was secreted and combined with its receptors on other cell types that were very nearby.  The hormone also combined with receptors on the cell from which it was released.  The hormone was in such low concentration that it did not have any affect upon cells that were not nearby even though those distant cells had receptors.  We would best classify this hormone as a(n)
  1. Endocrine hormone
  2. Paracrine hormone
  3. Autocrine hormone
  4. Both an autocrine hormone and a paracrine hormone
  5. Both an autocrine hormone and an endocrine hormone
5. The major difference between hormones that have intracellular receptors and those that have cell membrane receptors is that the former tend to be

  1. Larger
  2. Charged
  3. Amino acid derivatives
  4. Proteins
  5. Hydrophobic
6. All of the following are true about cortisol EXCEPT
  1. It is found in the blood adsorbed to steroid hormone binding globulin
  2. It is found in the blood bound to albumin
  3. Its receptors form dimers after binding
  4. Its activated receptors bind to glucocorticoid response elements
  5. The glucocorticoid response elements phosphorylate control enzymes
7. Concerning hormones that bind to receptors on the outer surface of the cell membrane, all of the following are true EXCEPT
  1. When hormones bind, the conformation of the receptor changes
  2. Some receptors are carbohydrates
  3. When hormones bind, the new conformation allows the receptor to react with another protein
  4. Eventually, the rate of control enzymes are effected
  5. Eventually, the transcription rates of specific mRNAs are affected
8. Signal transduction proteins
  1. are the proteins in the signal transduction pathway
  2. do not convert information from one form to another
  3. do not help to amplify the signal
  4. are not part of any second messenger cascade
  5. are never protein kinases
9. Proteins that contain a src homology 2 domain (SH2 domain)
  1. Have a phosphoserine residue that causes them to bind to other proteins
  2. Have a phosphotyrosyl residue that causes them to bind to other proteins
  3. Bind to any proteins that have a phosphoseryl residue
  4. Bind to proteins that have a phosphotyrosyl residue and a specific conformation
  5. Bind to proteins that have 2 sulfhydryl groups
10. All of the following are true in the Ras and MAP pathway EXCEPT.  When a growth factor binds to its receptor in the RAS and MAP pathway
  1. The occupied growth factor receptor autophosphorylates seryl residues
  2. Grb2 uses its Src homology domain to bind to the phosphorylated receptor
  3. Grb2 changes conformation and binds to the next protein (SOS) in the signal transduction pathway
  4. Ras exchanges GDP for GTP and activates the Raf, the first kinase in the MAP kinase pathway
  5. The MAP kinase pathway regulates transcription factors that regulate mRNA synthesis
11. All of the following are functions served by the phosphatidylinositol phosphates EXCEPT
  1. Phosphatidyl inositol bisphosphate  can be hydrolyzed to produce diacylglycerol, a second messenger
  2. Phosphatidyl inositol bisphosphate can be hydrolyzed to produce inositol trisphosphate, a second messenger
  3. Phosphatidyl inositol bisphosphate can be phosphorylated to produce Phosphatidyl inositol trisphosphate
  4. Phosphatidyl inositol trisphosphate can serve as a plasma membrane docking site for signal transduction proteins
  5. Phosphatidyl inositol trisphosphate will serve as a docking site for proteins containing a Src homology 2 domain
12. The reaction catalyzed by Phospholipase C involves all of the following EXCEPT
  1. Phosphitidylinositol bisphosphate as a substrate
  2. Diacylglycerol as a product
  3. Diacylglycerol phosphate as a product
  4. Inositol trisphosphate as a product
  5. Water as a substrate
13. All of the following are substrates and products of the reaction catalyzed by phosphatidylinositol 3’ kinase EXCEPT
  1. Phosphatidylinositol bisphosphate is a substrate
  2. Inositol trisphosphate is a substrate
  3. ATP is a substrate
  4. Phosphatidylinositol trisphosphate is a product
  5. ADP is a product
14. All of the following are true EXCEPT. Proteins with pleckstrin homology are
  1. Bound to phosphatidylinositol trisphosphate
  2. Tethered to the cell membrane when bound to phosphatidylinositol trisphosphate
  3. Bound because a signal transduction pathway has been activated
  4. Not tethered when there is no hormone at the receptor
  5. Vital participants in all signal transduction pathways
15. If a diabetic misses an injection of insulin, there will be
  1. An increase in the conversion of amino acids to glucose
  2. A stimulation of protein synthesis
  3. An increase the uptake of glucose into muscle cells
  4. An increase glycogen synthesis in muscle cells
  5. An increase in the utilization of blood glucose
16. Concerning the insulin receptor and the IRS protein
  1. The IRS protein phosphorylates the insulin receptor
  2. The beta-subunits of the receptor bind insulin, each subunit has a separate binding site
  3. Each beta-chain acts as a serine kinase and phosphorylates the other beta-chain
  4. The IRS binds to the phosphorylated beta-chains of the insulin receptor
  5. The IRS contains phosphoseryl residues
17. One of the insulin signal transduction pathways results in the activation of phosphatidylinositol 3' kinase.  Later in this pathway,
  1. Protein kinase B, an active serine kinase, dissociates from the membrane
  2. Protein kinase B, an active tyrosyl kinase, dissociates from the membrane
  3. Protein kinase B, an active serine kinase, associates with the membrane (becomes tethered)
  4. Protein kinase B, an active tyrosyl kinase, associates with the membrane (becomes tethered)
  5. Protein kinase A, an active serine kinase, associates with the membrane (becomes tethered)
18. Insulin is one of the hormones/growth factors that will activate the Ras and MAP kinase pathway.  Concerning this system, all of the following are true EXCEPT
  1. Grb2 binds to the phosphorylated IRS
  2. Grb2 binds directly to the seryl residues of the receptor alpha-chains
  3. Grb2 binds to the phosphorylated IRS using its Src2 domain
  4. Grb2 is a protein in a signal transduction pathway.
  5. The beta-subunits of the insulin receptor are phosphorylated on tyrosyl residues
19. In the insulin signal transduction pathway that leads to increases in the diacylglycerol and inositol trisphosphate second messengers, the signal transduction protein that binds to the IRS is
  1. Phospholipase C
  2. Phosphatidylinositol-3-kinase
  3. Grb2
  4. Ras
  5. Protein kinase B
20. When epinephrin or glucagon bind to their receptor on the membrane and activate the cAMP cascade, all of the following happen EXCEPT
  1. GDP dissociates from G-protein and GTP associates with G-protein
  2. The α-subunit of G-protein activates adenylate cyclase and cAMP is produced
  3. G-protein is freed from its tether and diffuses away from the cell membrane
  4. The α-subunit of G-protein hydrolyzes GTP and becomes inactive (will no longer bind adenylate cyclase)
  5. The α-subunit of G-protein bound to GDP must reassociate with the beta and gamma-subunits before binding to the occupied receptor
21. All G-proteins are activated by binding to GTP and loose their activity when they hydrolyze GTP to GDP.  However, their activity is quite different.  Which of the following is NOT correct?
  1. When active, Gαs activates adenylate cyclase
  2. When active, Gαs results in increased production of cAMP
  3. When active, Gαi results in the inhibition of adenylate cyclase
  4. When active, Gαq results in the activation of phospholipase C
  5. When active, Gαq results in the increased production of phosphatidylinositol trisphosphate
22. The protein product of the Ras oncogene is a mutated Ras protein.  All of the following would be true EXCEPT
  1. The Ras protein is a G-protein and functions as an internal clock
  2. G-proteins have evolved to stay active for a certain length of time
  3. Ras protein is active in cell growth and division
  4. Ras can mutate so that it is less active as a GTPase
  5. A less active GTPase would mean less stimulation of the MAP kinase pathway
23. When epinephrine binds to a(n) ____________ receptor, __________ is activated and there is an increase in the cellular concentration of ___________
  1. Beta                 Gαi                  inositol trisphosphate
  2. Alpha 1            Gαq                 inositol trisphosphate
  3. Beta                 Gαi                  diacylglycerol
  4. Alpha 1            Gαs                  cAMP
  5. Beta                 Gαq                 diacylglycerol and inositol trisphosphate
24. When the blood concentration of insulin is increases, less glucagon is produced and there is an increase in
  1. the activity of adenylate cyclase
  2. the activity of cAMP phosphodiesterase (3’, 5’-phosphodiesterase)
  3. binding of cAMP to the inhibitory subunits of protein kinase A
  4. cAMP
  5. protein kinase A activity
25. In many cells, adrenalin will bind to the α1 receptor and Gaq will be activated.  All of the following will happen EXCEPT
  1. Protein kinase activity will be decreased
  2. Inositol trisphosphate will cause the release of Ca++ from the endoplasmic reticulum
  3. Increased binding of Ca++ to calmodulin will occur
  4. Increased Ca++-calmodulin will bind to and activate calmodulin-binding proteins
  5. Protein kinase C will be activated by increased diacylglycerol
26. Assume that your patient is fasting and then eats a high carbohydrate meal.  The cAMP cascade of the liver will be terminated by all of the following EXCEPT
  1. Increased insulin will increase the production and release of glucagon
  2. Existing glucagon will be destroyed by the liver
  3. Increased cAMP phosphodiesterase activity (3’, 5’-phosphodiesterase)
  4. Increased activity of protein phosphatases
  5. G-proteins will hydrolyze GTP and will not be reactivated
27. Your patient has myasthenia gravis.  You might tell her all of the following EXCEPT
  1. She has an autoimmune disease
  2. She does not have enough acetylcholine receptors
  3. She has too much acetylcholine released
  4. She has trouble depolarizing the postsynaptic membrane
  5. Drugs that inhibit acetylcholine esterase can help her
28. Your patient suffers from anorexia nervosa and jogs every morning.  About 30 minutes into her jog, you would all of the following to be true EXCEPT
  1. Low blood sugar and low insulin have increased release of glucagon from α-cells of the pancreas
  2. Prolonged fasting and chronic exercise have increased the release of cortisol from the cortex of the brain
  3. Exercise has increased the release of epinephrine and norepinephrine from the adrenal medulla
  4. Glucagon, epinephrine and cortisol have all increased the release of glucose from the liver
  5. Glucagon, epinephrine and cortisol have all increased the release of free fatty acids from the adipose tissue
29. Your patient suffers from anorexia nervosa and eats very little.  Which of the following statements about glucagon is NOT true
  1. Glucagon is usually raised with fasting in response to low blood glucose
  2. Glucagon is usually raised with fasting in response to decreased insulin
  3. Glucagon reacts with receptors on liver cells and increases the release of glucose
  4. Glucagon reacts with receptors on adipose tissue and increases the release of free fatty acids
  5. Glucagon reacts with receptors on striated muscle cells and increases gluconeogenesis
30. Concerning the hormones glucagon, epinephrine, norepinephrine, and cortisol, which of the following is NOT true
  1. Epinephrine and norepinephrine can react with the same receptors
  2. Epinephrine and glucagon both activate the cyclic AMP cascade in liver
  3. Epinephrine and glucagon bind to different receptors on the liver cell membrane
  4. Glucagon, epinephrine, norepinephrine, and cortisol all cooperate in stimulating the production of glucose from amino acids in liver
  5. Glucagon usually increases glucose release by modulating the activity of transcription factors
31. If a thorough investigation is done, one finds that many hormones like insulin, glucagon and epinephrine (Best Answer)
  1. Can only regulate key enzymes in metabolic pathways
  2. Can only regulate the activity of transcription factors
  3. Can regulate key enzymes in metabolic pathways and regulate the activity of transcription factors
32. Dennis Veere has cholera.  Vibrio cholerae secrete an A toxin that is transported and processed in the gut cells.  All of the following are true EXCEPT
  1. Cholera A toxin cleaves ATP and transfers the ribose-5-phosphate groups to other proteins
  2. Cholera A toxin ADP-ribosylates the Gαs subunit of heterotrimeric G proteins, thereby inhibiting their GTPase activity
  3. Cholera A toxin increases the concentration of cAMP and activation of protein kinase A
  4. An overactive Protein kinase A phosphorylates the CFTR (cystic fibrosis transmembrane conductance regulator) chloride channel so that it remains permanently open
  5. Chloride, sodium and water move into the bowel lumen causing diarrhea and subsequent dehydration
33. One domain of Grb2 binds to the IRS because the domain has SH2 homology.  What determines if and where Grb2 binds to the IRS?
  1. A phosphotyrosyl residue
  2. A tyrosyl residue
  3. A phosphotyrosyl residue and a sequence of 3-6 amino acid residues
  4. A seryl residue
  5. A phosphoseryl residue that is the N-terminus of the SH2 domain and has N-acetyl group

Answers:

1. Answer: B. Chapter 11, Objective 1: Beginning with the release of a chemical messenger in response to a stimulus, list the common characteristics of all chemical messenger systems. Back to question 1.
2. Answer: A. Chapter 11, Objective 2: What is a signal transduction pathway? Name two types of targets of signal transduction pathways. Back to question 2.
3. Answer: D. Chapter 11, Objective 3: Beginning with the response to a stimulus, list the common characteristics of all chemical messenger systems as they apply to the chemical messenger acetylcholine at the neuromuscular junction. Use the terms nerve cell action potential, Ca2+-channel, vesicles, fusion, presynaptic membrane, acetylcholine, diffusion, acetylcholine receptors, gated ion channels, muscle cell action potential, and acetylcholinesterase. Back to question 3.
4. Answer: D. Chapter 11, Objective 4: Be able to determine when a chemical messenger is acting as an endocrine, paracrine, or autocrine substance. Back to question 4.
5. Answer: E. Chapter 11, Objective 5: What is a major difference between chemical messengers that are specific for intracellular receptors and those that are specific for plasma membrane receptors? Back to question 5.
6. Answer: E. Chapter 11, Objective 6: Describe the path taken by cortisol from the time it is released from the adrenal cortex until the time it affects gene transcription. Include serum albumin, steroid hormone binding globulin (SHBG), cortisol receptor, conformation change, nuclear translocation signal, dimerization, glucocorticoid response element (GRE), and regulation of gene transcription. Back to question 6.
7. Answer: B. Chapter 11, Objective 7: Concerning plasma membrane receptors for chemical messengers, how is the signal transduced? What are the two major effects upon the cell that result from chemical messenger binding? Back to question 7.
8. Answer: A. Chapter 11, Objective 8: What are signal transduction proteins? Back to question 8.
9. Answer: D. Chapter 11, Objective 9: When a protein contains a src homology 2 domain (SH2 domain), what does it bind to? Is the binding specific? Back to question 9.
10. Answer: A. Chapter 11, Objective 10: In the Ras and MAP kinase pathway, how does the occupied receptor activate Grb2? What is the last step in the pathway that is catalyzed by MAP-kinase and what is the effect? Back to question 10.
11. Answer: E. Chapter 11, Objective 12: What are the functions served by phosphatidylinositol phosphates in signal transduction? Back to question 11.
12. Answer: C. Chapter 11, Objective 13: What are the substrates and products of the reaction catalyzed by phospholipase C? Back to question 12.
13. Answer: B. Chapter 11, Objective 14: What are the substrates and products of the reaction catalyzed by phosphatidylinositol 3’ kinase? Back to question 13.
14. Answer: E. Chapter 11, Objective 15: What is the function of a pleckstrin homology domain? Back to question 14.
15. Answer: A. Chapter 11, Objective 16: What is the effect of insulin on protein synthesis and on glucose uptake and glycogen synthesis in muscle cells? Does this help to explain muscle wasting and hyperglycemia in a diabetic? Back to question 15.
16. Answer: D. Chapter 11, Objective 17: Be able to draw a cartoon of the insulin receptor that shows the cell membrane, two alpha-beta subunits, the membrane spanning region of the dimers, the insulin-binding site, the sites of tyrosine kinase domains, and the sites of auto-phosphorylation. Draw two IRS proteins bound to the receptor and indicate some of the sites phosphorylated on the IRS by the insulin receptor tyrosine kinases. Why do proteins bind to the phosphorylated IRS sites? Back to question 16.
17. Answer: A. Chapter 11, Objective 18: In the insulin signal transduction pathway that begins with the activation of phosphatidylinositol 3' kinase, name the down stream active kinase that dissociates from the membrane. Is this kinase a tyrosine or a serine/threonine kinase? Back to question 17.
18. Answer: B. Chapter 11, Objective 19: In the insulin signal transduction pathway that leads to the activation of MAP kinase, what is the signal transductioin protein that binds to the IRS? Why does it bind to the IRS? Back to question 18.
19. Answer: A. Chapter 11, Objective 20: In the insulin signal transduction pathway that leads to increases in the diacylglycerol and inositoltrisphosphate second messengers, What is the first signal transduction protein that binds to the IRS? Why does it bind to the IRS. Back to question 19.
20. Answer: C. Chapter 11, Objectives 21: Explain the sequence of reactions that occur following the binding of glucagon or epinephrine to a heptahelical receptor. Include the terms: glucagon, epinephrine, heterotrimeric G proteins, a subunit, bg complex, GDP, GTP, tethered, lipid anchor, adenylyl cyclase, ATP, cAMP, PPi, and hydrolysis How long does the Gas protein stay active? Back to question 20.
21. Answer: E. Chapter 11, Objectives 22: What is the effect of activating Gas, Gai , or Gaq? Back to question 21.
22. Answer: E. Chapter 11, Objective 11: A mutated form of the G-protein Ras is found in many cancers. How are these mutations thought to affect the cell? Use the term internal clock in your answer. Back to question 22.
23. Answer: B. Chapter 11, Objective 23: What is the response when epinephrine binds to an a1-adrenergic receptor? What is the response when epinephrine binds to a b-receptor? That is, what kind of G-protein is activated and what are the initial second messengers produced? Back to question 23.
24. Answer: B. Chapter 11, Objective 24: Name the enzyme that synthesizes cAMP, the enzyme that hydrolyses cAMP and the enzyme that is activated allosterically by cAMP. Which of these three enzyme reactions is affected by insulin? Back to question 24.
25. Answer: A. Chapter 11, Objective 25: When phosphatidyl inositol bisphosphate is hydrolyzed by phospholipase C, what is the next step in the signal transduction pathway for diacylglycerol? What are the next several steps in the signal transduction pathway for inositol trisphosphate? Use protein kinase C, target proteins, endoplasmic reticulum, calcium, calmodulin, and calmodulin binding proteins in your answer. Back to question 25.
26. Answer: A. Chapter 11, Objective 26: Glucagon is released when blood sugar is low. How is its signal terminated (or lowered) following a high carbohydrate meal that increases the blood sugar? Back to question 26.
27. Answer: C. Chapter 11, Objective 27: Concerning Mya Sthenia who has myasthenia gravis, explain how her chemical messenger system differs from a normal person. How did this happen? Why do the anticholinesterase drugs do to temporarily alleviate the problem? Back to question 27.
28. Answer: B. Chapter 11, Objective 28: Concerning Ann O'Rexia who has been fasting and is jogging, what was the stimulus for the release of glucagon, epinephrine, norepinephrine, and cortisol? From what cells and what tissue did glucagon originate? From what tissues did epinephrine, norepinephrine, and cortisol originate? What is the effect of all these hormones upon the release of glucose from liver and free fatty acids from adipose tissue? Back to question 28.
29. Answer: E. Chapter 11, Objective 29:Concerning Ann O'Rexia who has been fasting, why is her blood glucagon increased? Why does glucagon have an effect upon adipose and liver tissue but not upon skeletal muscle tissue? Back to question 29.
30. Answer: E. Chapter 11, Objective 30: Concerning Ann O'Rexia, do glucagon, epinephrine, norepinephrine, and cortisol react with the same receptors, use the same pathways, and elicit the same cellular response? Back to question 30.
31. Answer: C. Chapter 11, Objective 31: Concerning Ann O'Rexia, what are the two general mechanisms (ways) that glucagon, epinephrine and other hormones use to elicit a response in target cells? Back to question 31.
32. Answer: A. Chapter 11, Objective 32: Concerning Dennis Veere who has cholera, how does the cholera A toxin change the metabolism of the intestinal cell? Use ADP-ribosylation factor, NAD, ADP ribose, ADP-ribosylates, Gas subunit, adenyl cyclase, cAMP, CFTR channel, chloride ion, sodium, and diarrhea in your answer. Back to question 32.
33. Answer: C. Chapter 11, Objectives 10 and 17 : In the Ras and MAP kinase pathway, how does the occupied receptor activate Grb2? What is the last step in the pathway that is catalyzed by MAP-kinase and what is the effect? and Be able to draw a cartoon of the insulin receptor that shows the cell membrane, two alpha-beta subunits, the membrane spanning region of the dimers, the insulin-binding site, the sites of tyrosine kinase domains, and the sites of auto-phosphorylation. Draw two IRS proteins bound to the receptor and indicate some of the sites phosphorylated on the IRS by the insulin receptor tyrosine kinases. Why do proteins bind to the phosphorylated IRS sites? Back to question 33.