Garrett Chapter 32-copy

All are catecholamine neurotransmitters EXCEPT: A. g-aminobutyrate (GABA). B. L-dopa. C. dopamine. D. epinephrine. E. norepinepherine

A

All are domains of receptor tyrosine kinase EXCEPT: A. adenylyl cyclase activity domain. B. glycosylated extracellular receptor-binding domain. C. a single transmembrane a-helix. D. intracellular tyrosine kinase domain. E. regulatory domain with phosphorylation sites

A

All are results of the phospholipase C activity mediated by hormone binding, signal transduction and eventually Ca++ release into the cytoplasm EXCEPT: A. an increase in guanylyl cyclase activity. B. the phosphorylation of specific proteins. C. activation of protein kinases by calcium complexed with calmodulin. D. the release of diacylglycerol from membrane phospholipids. E. the release of IP3.

A

During an action potential, which of the following is directly responsible for restoration of resting membrane potential? A. efflux of K+ ions B. efflux of Na+ ions C. influx of K+ ions D. influx of Na+ ions E. efflux of Cl- ions

A

G-proteins are involved in directly mediating the activity of the following EXCEPT: A. calmodulin. B. adenylyl cyclase. C. phospholipase C-b. D. phospholipase A2. E. ion channels for K+ and other ions.

A

In G-proteins, binding of GTP causes ____ association and association with effector proteins like ____. A. Ga; adenylyl cyclase B. Ga; GTPase C. Gb; Ga D. Gb; Gg E. Gg; Ga

A

In a neuron, when voltage-gated Na+ channels have just closed, which of the following is true? A. the membrane is less polarized than at rest B. the membrane is more polarized than at rest C. the membrane is polarized to the same degree as at rest D. the membrane is hyperpolarized E. none of the above are true

A

Phospholipase C-g is activated by ____ and is homologous with phospholipase ____ in the X and Y domains. A. receptor tyrosine kinase; C-b B. receptor tyrosine kinase; C-a C. protein kinase A; C-b D. protein kinase A; C-a E. all are true

A

Rapid influx of Ca++ into the cytoplasm can occur as a result of the binding of hormones to a receptor activating phospholipase C activity. The increased level of Ca++ is derived from all of the following EXCEPT: A. lysozymes. B. calciosomes. C. endoplasmic reticulum. D. extracellular stores through Ca++ channels in the plasma membrane. E. all of the above.

A

Receptor tyrosine kinases have been called ____ as a result of their ____ and ____. A. membrane-associated allosteric enzymes; induced conformation changes; oligomeric interactions B. adrenergic receptors; binding insulin; binding epinephrine C. GTP-binding proteins; GTPase activity; guanylyl cyclase activity D. multi-TMS receptors; complex structure; G-protein binding E. none of the above

A

The hydrolysis of PIP2 by phospholipase C-b yields what membrane-soluble secondary messenger? A. diacylglycerol (DAG) B. phosphatidylinositol (PI) C. phosphatidylinositol-4,5-bisphosphate (PIP2) D. inositol-1,4,5-trisphosphate (IP3) E. inositol-1,4-bisphosphate (IP2)

A

The phospholipid that is hydrolyzed to stimulate ceramide-activated protein kinase is: A. sphingomyelin. B. phosphatidylinositol-4,5-bisphosphate. C. phosphatidylinositol-4-phosphate. D. phosphatidylcholine. E. phosphatidylinositol.

A

Which of the following doe NOT correctly pair a hormone with its function? A. ACTH - promotes production of thyroxin B. calcitonin - regulates plasma Ca2+ C. FSH - stimulates processes within the gonads D. insulin - regulates metabolism and blood glucose E. prolactin - stimulates milk production

A

Botulism toxin strongly: A. inhibits acetylcholinesterase. B. inhibits acetylcholine release. C. stimulates acetylcholinesterase. D. inhibits acetylcholine binding to specific acetylcholine receptors. E. opens ligand-gated ion channels.

B

Calmodulin exhibits all of the following characteristics EXCEPT: A. its conformation is sensitive to Ca++ binding. B. it contains a basic amphiphilic alpha helix which interacts with target proteins. C. it modulates the activity of many protein kinases. D. it contains one or more helix-loop-helix motifs (EF-hands) which bind the Ca++ ion. E. all are characteristics.

B

G-proteins are associated with which receptor superfamily? A. oligomeric ligand-gated ion channels B. 7-transmembrane segment (7-TMS) receptors C. cell adhesion protein receptors D. single-transmembrane segment catalytic receptors E. none of the above

B

How does extracellular hormone binding activate intracellular tyrosine kinase activity? A. conformational change induced active site activation B. conformational change induced oligomeric association and phosphorylation C. induced mRNA synthesis D. activation of specific phospholipases E. all are true

B

Like acetylcholine, ____ and ____ are excitatory, but must be removed by ____. A. Asp; Lys; degradation B. Asp; Gly; reuptake C. Glu; Gln; reuptake D. Gln; Lys; degradation E. Lys; Arg; degradation

B

The binding of hormone to G-protein coupled receptor stimulates the sequence: A. binding of Ga (GTP) activates adenylyl cyclase B. Ga(GTP) dissociates and re-associates with Gbg C. rapid exchange of GDP for GTP on Ga D. GTPase of Ga hydrolyzes GTP to GDP E. Ga dissociates from Gbg A. B, C, A, D, E B. C, E, A, D, B C. C, E, B, D, A D. D, A, C, E, B E. E, A, D, B, C

B

The insulin receptor is in what class of tyrosine kinase receptors? A. Class I with 2 Cys-rich repeat sequences B. Class II with a2b2 tetrameric structure C. Class III with multiple immunoglobulin-like extracellular domains D. Class IV with a glycosylated protein domain E. Class V with a lipid-rich hydrophobic domain

B

The members of the protein kinase C family that are regulated by Ca++, by diacylglycerol and by phosphatidylserine are called the: A. atypical PKCs. B. conventional PKCs. C. modified PKCs. D. novel PKCs. E. all of the above.

B

The original phorbol esters are natural products that mimic ____ by binding and activating ____ that potentiate the effects of ____. A. hormones; PKA; Ca2+ B. DAG; PKC; carcinogens C. cAMP; PKA; glucagon D. Ca2+; PKC; Ca2+ E. PIP2; CaM; Li+

B

The proper metabolic sequence is: A. tyrosine B. epinephrine C. norepinepherine D. L-dopa E. dopamine A. A, C, D, E, B B. A, D, E, C, B C. D, A, E, B, C D. D, E, A, B, C E. E, D, A, B, C

B

Transient increases in cytoplasmic Ca2+ levels can activate all EXCEPT: A. muscle contraction. B. glucose uptake. C. exocytosis. D. glycogen metabolism. E. all are true

B

____ of Tyr527 in the SH2 domain of protein tyrosine kinase pp60c-src ____ tyrosine kinase activity by moving an "activation loop" ____ the active site. A. Phosphorylation; activates; away from B. Phosphorylation; inhibits; into C. Dephosphorylation; inhibits; away from D. Dephosphorylation; activates; into E. none are true

B

All are enzymes in the enzyme cascade for activation of glycogen phosphorylase EXCEPT: A. adenylyl cyclase. B. protein kinase A. C. hormone sensitive lipase. D. phosphorylase kinase. E. all are in the cascade

C

All are unifying features of polypeptide hormones EXCEPT that they are: A. originally synthesized with signal sequences. B. synthesized as inactive preprohormones. C. activated from preprohormones to hormones by phosphorylation. D. may produce several different peptide hormones with suitable processing. E. all are true

C

Calcium binding proteins all possess two or more characteristic peptide domains for Ca++ binding that consist of a short a-helix, a loop of 12 amino acids and a second a-helix (helix-loop-helix) that is called: A. basic region leucine zipper. B. zinc finger. C. EF hand. D. beta-beta. E. none are true.

C

It is believed that many general anesthetics work by prolonging the open time of GABA receptors. What type of channel does the GABA receptor mediate? A. sodium B. calcium C. chloride D. potassium E. all are true

C

Lithium salts have been used for years for the treatment of manic depression. Although its mechanism of action at the molecular level is far from clear, it has been shown that Li+: A. alters the conformation of a number of plasma protein receptors. B. increases the GTPase activity of G-proteins. C. inhibits a number of enzymes in phosphoinositide metabolism. D. inhibits Ca++ release from cytoplasmic organelles. E. activates protein kinase A much like cAMP does.

C

Nitroglycerine is a potent ____ because of the release of ____. A. antioxidant; O2 B. vasoconstrictor; NO. C. vasodilator; NO. D. muscle tensor; O2 E. all are true

C

____ act as an antidepressant by ____ levels of catacholamines in the brain. A. Tricyclics; increasing B. Tricyclics; decreasing C. Monoamine oxidase inhibitors; increasing D. Monoamine oxidase inhibitors; decreasing E. Monoamine oxidases; decreasing

C

A muscarinic receptor is a subclass of ____ receptor, and can be inhibited by ____. A. GABA; atropine B. GABA; acetylcholine C. acetylcholine; GABA D. acetylcholine; atropine E. acetylcholine; muscarine

D

A specific GTPase-activating protein (GAP) binds to and activates: A. the G-protein. B. the plasma membrane receptor. C. adenylyl cyclase. D. the GTPase activity of the Ras protein. E. none of the above

D

Each of the following statements is true EXCEPT: A. epinephrine is an amino acid derivative B. steroid hormones can enter cells and regulate transcription C. insulin is a polypeptide hormone D. progesterone is a polypeptide hormone E. all of the above are true

D

Neurotransmitters must be removed from the synaptic cleft to: A. promote prolonged stimulation of the postsynaptic cell. B. prevent prolonged stimulation of the presynaptic cell. C. promote prolonged stimulation of the presynaptic cell. D. prevent prolonged stimulation of the postsynaptic cell. E. none of the above.

D

Steroid hormones, such as glucocorticoids, effect their action by: A. binding to a plasma membrane receptor and then entering the cell. B. binding the plasma membrane receptor, which stimulates the receptor to enter the cell. C. entering into the cell and affecting the production of secondary messengers. D. entering into the cell and then acting as transcription regulators. E. none of the above

D

The acrosome reaction, involving ion channel induced release of acrosomal enzymes used by sperm to attack the egg, is induced by: A. estrogen. B. testosterone. C. dihydrotestosterone (DHT). D. progesterone. E. cortisol.

D

The amount of cAMP generated in the cytoplasm is dependent on the: A. activity of adenylyl cyclase only. B. activity of the phosphodiesterase only. C. the length of time the GTP remains bound to the Ga-protein only. D. all of the above. E. none of the above.

D

The effects of ethanol on the brain arise in part from opening of ____ receptor Cl- channels. A. glycine B. aspartate C. glutamate D. g-aminobutyrate (GABA) E. all are true

D

The second messenger produced from the hydrolysis of PIP2 that activates the increase of Ca++ concentrations in the cytoplasm is: A. diacylglycerol (DAG). B. phosphatidylinositol (PI). C. phosphatidylinositol-4,5-bisphosphate (PIP2). D. inositol-1,4,5-trisphosphate (IP3). E. inositol-1,4-bisphosphate (IP2).

D

Which of the following statements regarding neurons and the action potential is NOT true? A. efflux of K+ ions leads to a brief hyperpolarization of the cell membrane B. the resting membrane potential is approximately -80mV C. sodium ions that enter an axon through sodium channels in a given axonal region diffuse further along the axon, depolarizing the next axonal region D. in myelinated axons, sodium channels are distributed evenly E. all of the above are true

D

Acetylcholinesterase: A. catalyzes synthesis of acetylcholine. B. is regulated by binding of cocaine. C. hydrolyzes acetylcholine inside the presynaptic cell. D. normally functions to prolong stimulation of the postsynaptic cell. E. must be secreted into the synaptic cleft.

E

All are characteristic of EF-hand proteins EXCEPT: A. EF-hand domains usually are arranged so that two EF-hand domains directly contact each other. B. EF-hand proteins dramatically change conformation upon binding Ca++ ions. C. Conformational changes promote binding of the EF-hand protein with its target protein(s). D. CaM (a EF-hand protein) binds target protein with basic amphiphilic alpha helix (Baa helix) motifs. E. All are characteristic.

E

All are components of the G-protein-coupled receptors (GPCRs) hormone signal transduction unit EXCEPT: A. protein kinase A. B. adenylyl cyclase. C. hormone receptor. D. G-protein. E. all of the above.

E

All are inhibitors of acetylcholinesterase EXCEPT: A. sarin. B. malathion. C. parathion. D. tabun. E. all are inhibitors.

E

Cancerous tumors may develop from all of the following EXCEPT: A. mutations in several proto-oncogenes or tumor suppression genes. B. interactions among two or more oncogene products. C. simultaneous mutations in a proto-oncogene and both copies of a tumor suppression gene. D. overlapping growth-control mechanisms that when one is compromised by mutation, others take over. E. all are true.

E

Characteristics of myasthenia gravis include all EXCEPT: A. chronic disorder causing muscle weakness. B. autoimmune disease. C. individual's antibodies bind their own acetylcholinesterase receptors. D. physiostigmine and neostigmine are used to treat myasthenia gravis. E. all are true.

E

Hormones and other signal molecules bind with ____ affinities to their receptors and are produced at concentrations ____ their KD values. A. low; far above B. moderate; far above C. moderate; equivalent to D. high; far below E. very high; equivalent to

E