Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
99 Cards in this Set
- Front
- Back
|
1. There are two important components in the hardware responsible for maintaining resting potential of a cell. One is the so-called Na+/K+ ATPase. What is the other component?
A. Voltage-operated Ca2+ channels B. Ryanodine receptors C. K+ leak channels D. None of the above |
C. K+ leak channels
|
|
|
2. In general ligand-operated ion channels display less ion specificity than voltage-operated channels
(i.e. which ion they allow to pass through the pore). This is because: A. Ligand-operated ion channels lack ion filters B. Ligand-operated ion channels have more subunits, thus wider pores C. The pore of voltage-operated channels possesses a Mg2+ ion which blocks passage of unwanted ions D. None of the above |
B. Ligand-operated ion channels have more subunits, thus wider pores
|
|
|
3. If a K+ leak channel opens in a cell that is at its resting potential, in which direction do the K+ ions flow:
A. Into the cell, causing a depolarization B. Out of the cell, causing a hyperpolarization C. A transitory efflux followed by an influx D. None of the above |
B. Out of the cell, causing a hyperpolarization
|
|
|
4. The resting potential for a cell is generally in the range:
A. +50 mV to +70 mV B. +75 mV to +100 mV C. -50 mV to -70 mV D. None of the above |
C. -50 mV to -70 mV
|
|
|
5. What determines the direction an ion will flow through an ion channel on the membrane of cells?
A. The charge of the ion relative to the potential of the cell B. The chemo-equlibrium point of the ion, which depends on both the concentration gradient of the ion and on the charge of the ion C. Only the concentration gradient of the ion is of major importance D. None of the above |
B. The chemo-equlibrium point of the ion, which depends on both the concentration gradient of
the ion and on the charge of the ion |
|
|
6. The four different subunit types of the nicotinic receptor are structurally very similar. This is because:
A. They are all products of the same gene, with post-translational modification giving rise to the different subunits B. Their genes are believed to have been derived from the same ancestral gene. C. They share functional domains with G protein-coupled receptors D. None of the above |
B. Their genes are believed to have been derived from the same ancestral gene.
|
|
|
7. Producing a hydropathy profile of a protein can be useful because:
A. One can determine if the protein has potential membrane spanning regions B. One can predict from the profile which end of the protein will be the N-terminal and which end will be the C-terminal. C. One can use the profile to predict if the protein has evolved from an accessorial gene. D. All of the above. |
A. One can determine if the protein has potential membrane spanning regions
|
|
|
8. The enzyme reverse transcriptase is used to produce a cDNA library. This enzyme:
A. Transcribes genomic DNA, thus making multiple copies of genes B. Transcribes RNA into DNA C. Transcribes mRNA (messenger RNA) into tRNA (transfer RNA) D. None of the above |
B. Transcribes RNA into DNA
|
|
|
9. Site-directed mutagenesis is a method that is often used when molecular biologists are testing models of receptors (e.g. studying functional domains). In site-directed mutagenesis:
A. A nucleotide within cDNA is altered (substituted for another) so there is an alteration in a codon within the cDNA and thus ultimately which amino acid will be found in the protein B. Animals are treated with mutagens (mutation inducing compounds) and their offspring selected for interesting mutations in sites within the gene that code functional domains for receptors C. Mutagens are introduced into specific sites in the brain in order to induce mutations in functional domains of receptors operating in these brain regions D. None of the above |
A. A nucleotide within cDNA is altered (substituted for another) so there is an alteration in a codon
within the cDNA and thus ultimately which amino acid will be found in the protein |
|
|
10. Orphan receptors are receptors that:
A. Are predicted to be receptors from their structure but have no known ligand B. Have a known ligand but are of an unknown structure C. Bind the neuropeptide orphanannie D. None of the above |
A. Are predicted to be receptors from their structure but have no known ligand
|
|
|
11. Which amino acid would you expect to find frequently in the ion pore domain of an ion channel?
A. Phenylalanine B. Serine C. Lysine D. Glutamic acid |
B. Serine
|
|
|
12. Which amino acid would you expect to find in the ion filter domain of the GABAa receptor.
A. Phenylalanine B. Serine C. Lysine D. Glutamic acid |
C. Lysine
|
|
|
13. The enzyme glutamic acid decarboxylase is an important enzyme because:
A. It is responsible for the degradation of glutamic acid in the synapse, thus terminating glutamate signaling B. It is responsible for producing an inhibitory neurotransmitter C. It is a key enzyme in the tricarboxylic acid (TCA ) cycle D. None of the above |
B. It is responsible for producing an inhibitory neurotransmitter
|
|
|
14. Serines and threonines on intracellular loops of receptors are often targets for:
A. Kinases B. Proteolytic enzymes C. Acetylations D. None of the above |
A. Kinases
|
|
|
15. Benzodiazepines have a “calming” or sedative effect because:
A. They act on metabotropic receptors to reduce membrane tension B. They act on opiate receptors as obligatory co-agoinists C. They down regulate stimulatory receptor mechanisms D. They potentiate the actions of GABA |
D. They potentiate the actions of GABA
|
|
|
16. For most ion channel receptors, the transmembrane segments of all the subunits contribute in the formation of the ion pore. Glutamate ionotropic receptors are an exception to this. For these receptors the pore is formed from:
A. One subunit, designated the P-subunit, forming the pore B. A repulsion between the membrane lipid bilayer and charged glutamic acid groups within the receptor subunits, thus creating a water filled hydrophilic pore C. Each subunit contributes a P-element, which pushes into the membrane to form a pore D. None of the above |
C. Each subunit contributes a P-element, which pushes into the membrane to form a pore
|
|
|
17. Among the glutamate ionotropic receptors the N-methyl D-aspartate (NMDA) receptor is considered somewhat unique because:
A. It generates biphasic responses, first stimulatory, then inhibitory B. It is highly permeable to Ca2+ and is therefore considered to be a ligand-operated Ca2+ channel C. It is activated by two stimulatory neurotransmitters, namely aspartate and glutamate D. All of the above |
B. It is highly permeable to Ca2+ and is therefore considered to be a ligand-operated Ca2+ channel
|
|
|
18. The NMDA receptor has the amino acid glycine as a “co-agonist” but glutamate is generally considered to be the neurotransmitter responsible for activating the receptor. Why is glutamate and not glycine generally considered the neurotransmitter for regulating NMDA receptor activity?
A. Because the extracellular concentration of glycine is sufficient to keep the glycine binding site occupied, thus making glutamate, and not glycine, the critical factor for activating the receptor B. Because glycine is not a neurotransmitter C. Because the amino acid lysine can substitute for glycine in its role as “co-agoinst” D. None of the above |
A. Because the extracellular concentration of glycine is sufficient to keep the glycine binding site
occupied, thus making glutamate, and not glycine, the critical factor for activating the receptor |
|
|
19. The NMDA receptor is constructed from NR1 and NR2 subunits. Which subunit possesses the binding site for glutamate?
A. The NR2 subunit B. The NR1 subunit C. The binding site is formed from an interaction between NR1 and NR2 D. The location of the binding site is unknown |
A. The NR2 subunit
|
|
|
20. When a voltage-operated Ca2+ channel opens it forms a microdomain of Ca2+ inside the cell (rather than a massive, widely dispersed Ca2+ signal). This microdomain forms because:
A. There are pumps on the membrane to immediately pump the Ca2+ out of the cell, thus not allowing a massive Ca2+ signal to develop B. The Ca2+ is pumped into the lumen of the endoplasmic reticulum, thus not allowing a massive Ca2+ signal to develop C. The Ca2+ binds to Ca2+ binding proteins in the cytoplasm, thus not allowing a massive Ca2+ signal to develop D. All of the above |
D. All of the above
|
|
|
21. The concentration of the ion Ca2+ is carefully regulated in a cell because:
A. High Ca2+ is toxic to the cell B. Ca2+ gradients are responsible for maintaining Na+ and K+ channel activity C. Ca2+ gradients are responsible for setting the resting potential and thus changes in Ca2+ have adverse effects on membrane potential D. None of the above |
A. High Ca2+ is toxic to the cell
|
|
|
22. Ca2+-induced Ca2+-release (CICR) is a process whereby:
A. Ca2+ induces an influx of Ca2+ from the extracellular compartment B. Ca2+ induces a mobilization of Ca2+ from intracellular Ca2+ stores C. Ca2+ activates kinases which it turn activates voltage-operated Ca2+ channels leading to Ca2+ influx D. None of the above |
B. Ca2+ induces a mobilization of Ca2+ from intracellular Ca2+ stores
|
|
|
23. The NMDA receptor is considered a “coincidence detector” because:
A. It can detect the simultaneous occurrence of a membrane depolarization and the activation of the AMPA receptor B. It can detect a membrane depolarization occurring (almost) simultaneously with an influx of Mg2+ ions C. It can detect the presence of Ca2+ waves, occurring together with membrane depolarizations D. It can detect the presence of extracellular glutamate, occurring (almost) simultaneously with a membrane depolarization |
D. It can detect the presence of extracellular glutamate, occurring (almost) simultaneously with a
membrane depolarization |
|
|
24. Some neurons are capable of “back propagation” of the action potential (propagation into the dendrites). Such back propagation is important because it:
A. Allows neurons to signal in both directions, adding to the efficiency of neuronal communication B. Allows dendrites to participate in setting the rest potentials of the neuron C. Lifts the Mg2+ block of the NMDA receptor D. Activates voltage-operated Mg2+ channels, allowing Mg2+ to participate in coincidence detection |
C. Lifts the Mg2+ block of the NMDA receptor
|
|
|
25. The subunits of voltage-operated channels (K+, Na+ and Ca2+) display a high degree of homology. The reason for this is believed to be:
A. Because they are all derived from voltage operated Na+ channels (i.e. Na+ channels were the first to arise, giving rise to all other channel types) B. Prokaryotic inward rectifier K+ channels gave rise to all voltage-operated channels C. Primitive G protein-coupled receptors evolved into the voltage-operated channels D. None of the above |
B. Prokaryotic inward rectifier K+ channels gave rise to all voltage-operated channels
|
|
|
26. Post-synaptic density protein 95 (PSD95) is:
A. A regulatory subunit of post-synaptic G protein-coupled receptors B. An intracellular protein which anchors NMDA receptors within the synapse C. A membrane bound protein which is responsible for organizing the post-synaptic extracellular space D. None of the above. |
B. An intracellular protein which anchors NMDA receptors within the synapse
|
|
|
27. Which group, on the side chain of amino acids within proteins, does Protein kinases phosphorylate?
A. The N-terminal amino group B. The carboxyl group of acetic amino acids C. The hydroxyl group D. The tertiary amino group of basic amino acids |
C. The hydroxyl group
|
|
|
28. The serine/threonine kinases are called serine/threonine because:
A. Hydroxyl groups on the amino acids serine and threonine are the targets for these enzymes B. There are many serines and threonines within the active (catalytic) site of these kinases C. Serine and threonine are important obligatory agonists for this class of kinases D. None of the above |
A. Hydroxyl groups on the amino acids serine and threonine are the targets for these enzymes
|
|
|
29. Serine/threonine kinases are generally found in the cytoplasm of a cell, where they are often
regulated by: A. Second messenger molecules generated by other enzymes B. Enzymes that generate ATP C. Monovalent cations D. None of the above |
A. Second messenger molecules generated by other enzymes
|
|
|
30. Tyrosine kinase receptors are generally found:
A. In the cytoplasm where they can be activated by other kinases B. On the plasma membrane, where they can bind with extracellular ligands and phosphorylate intracellular proteins C. In the endoplasmic reticulum, where they regulate transport processes D. None of the above |
B. On the plasma membrane, where they can bind with extracellular ligands and phosphorylate
intracellular proteins |
|
|
31. The ligand binding site of tyrosine kinase receptors often possess disulphide bridges. The purpose of these disulphide bridges is:
A. To form loops in the receptor so that the ligand binding domain can interact with the kinase domain of the receptor (kan niet? ´de ligand gaat niet door de membraan naar het kinase domein’) B. To provide for covalent bridges to another receptors, thus forming receptor dimmers C. To form a pocket for ligand binding D. All of the above |
C. To form a pocket for ligand binding
|
|
|
32. Tyrosine kinase receptors possess only one transmembrane domain and yet they are quite stable within the membrane (i.e. they do not become detached very easily from the membrane). This is because:
A. They possess positively charged amino acids near the membrane spanning region (transmembrane region) which hold them in place B. They form covalent bonds with lipids of the lipid bilayer, thus anchoring themselves to the membrane C. They are held in place by anchoring proteins D. None of the above |
A. They possess positively charged amino acids near the membrane spanning region
(transmembrane region) which hold them in place |
|
|
33. Tyrosine kinase receptors possess only one transmembrane domain and yet, with ligand binding, they are able to transduce a signal across the membrane. They can do this because:
A. Negatively charged amino acids within the transmembrane region interact with positively charged amino acids near the membrane, thus transducing the signal B. The alpha-helix structure of the transmembrane region acts as a spring during the signal transduction process C. Ligand binding induces transmembrane regions of the receptors to fold, thus inducing a structural change in the catalytic domain of the receptor D. None of the above. |
D. None of the above.
|
|
|
34. The intracellular domain of tyrosine kinase receptors possess a large number of tyrosines. The purpose of these tyrosines is:
A. To act as a target for tyrosine kinases B. To form a part of the catalytic domain of the receptor C. To give stability to the catalytic domain D. None of the above. |
A. To act as a target for tyrosine kinases
(or B. To form a part of the catalytic domain of the receptor) |
|
|
35. Substrates for tyrosine kinase receptors possess Src homology region 2 (SRC-2) domains. The purpose of these domains is:
A. To bind Src, thus initiating intracellular signaling cascades B. To target the substrate to tyrosine kinase receptors C. To bind to anti-Src sequences, thus regulating the activity of tryrosine kinase receptors D. None of the above |
B. To target the substrate to tyrosine kinase receptors
|
|
|
36. Viral Src (vSRC) is:
A. An oncogene coding for a tyrosine kinase B. An oncogene coding for a transcription factor which induces tumors C. An oncogene coding for a mitochondrial protein D. None of the above. |
A. An oncogene coding for a tyrosine kinase
|
|
|
37. When a tyrosine kinase receptor is activated the first protein that it phosphorylates is:
A. A voltage operated Ca2+ channel so that Ca2+ can cooperate with the kinase in the regulation of the cell B. A transcription factor associated with the expression of the kinase, thus ensuring the presence sufficient receptor to respond to the increasing demands of the cell C. Another tyrosine kinase receptor molecule, thus producing substrate recognition sites within the kinase D. None of the above |
C. Another tyrosine kinase receptor molecule, thus producing substrate recognition sites within
the kinase |
|
|
38. In phosphorylations catalyzed by tyrosine kinase receptors, the source of the phosphorous is:
A. Phosphorous groups attached to hydroxyl groups of tyrosines within the catalytic site B. Phosphorous groups transferred from Src homology region 2 domains C. ATP D. None of the above |
A. Phosphorous groups attached to hydroxyl groups of tyrosines within the catalytic site
|
|
|
39. The activation of GTPase activating protein (GAP) by tyrosine kinase receptors will in turn:
A. Inactive G proteins, thus inhibiting G protein signaling B. Lead to ATP hydrolysis, thus releasing energy for intracellular signaling cascades C. Initiate an auto-feedback mechanism by stimulating the hydrolysis of GTP in the active site of the kinase D. None of the above |
A. Inactive G proteins, thus inhibiting G protein signaling
|
|
|
40. Phospholipase C gamma (PLC.) is an enzyme which:
A. Possess a Src homology region 2 domain B. Catalyzes the breakdown of membrane phospholipids C. Can generate second messenger molecules D. All of the above |
D. All of the above
|
|
|
41. Diacylglycerol (DAG) is a lipid that:
A. Can combine with inositol triphosphate (IP3) to form a signaling complex B. Can bind to and activate a kinase C. Can interact with and activate membrane bound receptors D. None of the above |
B. Can bind to and activate a kinase
|
|
|
42. Protein kinase C (PKC) is a kinase that:
A. Is activated through its phophorylation by PLC-gamma B. Possesses a binding site for diacylglycerol (DAG) C. Is constructed from multiple subunits D. All of the above |
B. Possesses a binding site for diacylglycerol (DAG)
|
|
|
43. The activation of the IP3 Receptor can:
A. Initiate Ca2+ induced Ca2+ release B. Initiate Ca2+ waves C. Lead to the activation of Ca2+ calmodulin dependent protein kinases D. All of the above. |
D. All of the above.
|
|
|
44. Phospholipase C-gamma (PLC.) and PLCß are:
A. The same protein, with it being referred to as “gamma” if it is associated with the membrane and “beta” if it is free in the cytoplasm of the cell B. Two different lipases, one activated by tyrosine kinase receptors and the other activated by G protein-coupled receptors C. Subunits of the PLC enzyme, with both subunits required to make the biologically active lipase D. None of the above |
B. Two different lipases, one activated by tyrosine kinase receptors and the other activated by G
protein-coupled receptors |
|
|
45. When tyrosine kinase receptors are activated by ligands they often undergo “clustering” on the membrane. Such clustering is followed by endocytosis. The function of this endocytosis may be:
A. To down-regulate the receptor mechanism, whereby the receptor is send to lysosomes for destruction B. To desensitize the receptor mechanism, whereby the receptors are temporarily internalized but eventually are returned to the membrane C. To bring activated receptor into the cell to phosphorylate proteins inside the cell D. All of the above. |
D. All of the above.
|
|
|
46. Posphatases are enzymes that dephosphorylate proteins. A characteristic of phosphatases is:
A. That their activity, unlike the kinases, is unregulated B. That they show very low substrate specificity, so that most phosphatases can deposphorylate serines, threonines as well as tyrosines C. That they possess transmembrane regions and are thus their distribution is restricted to the membrane D. None of the above |
D. None of the above
|
|
|
47. Viral oncogenes are thought to be derived from the eukaryotic genome because:
A. Their promoters resemble promoters of eukaryotic genes B. They possess an intron-exon structure C. They have a double helix structure D. None of the above |
B. They possess an intron-exon structure
|
|
|
48. Tropomyosin-receptor kinase (Trk) is a product of a viral oncogene. Proto-oncogenes of Trk
represent: A. Receptors for neurotrophins B. Src homology region 2 analogues C. Cytoplasmic serine/threonine kinases D. None of the above |
A. Receptors for neurotrophins
|
|
|
49. As the name implies, neurotrophins stimulate neurons. The release of neurotrophins can be
constitutive (i.e. via a Ca2+-independent pathway). One of the functions of this constitutive secretion of neurotrophin is: A. To signal to other brain areas that the neuron is active B. To get rid of excess neurotrophin C. For maintenance of the neuron D. None of the above |
C. For maintenance of the neuron
|
|
|
50. The source of Ca2+ for the regulated release of neurotransmitters is usually an influx through voltage-operated Ca2+ channels. For the regulated secretion of neurotrophins it would seem that the an important source of Ca2+ is:
A. Also voltage operated Ca2+ channels B. Ca2+ mobilized from intracellular Ca2+ stores C. Ca2+ released from Ca2+ binding proteins D. None of the above |
B. Ca2+ mobilized from intracellular Ca2+ stores
|
|
|
51. The C-terminal region of Trk receptors can bind dynein, a retrograde transport protein. What possible significance might this finding have concerning Trk receptor signaling?
A. Dynein could be involved in transporting newly synthesized receptors to nerve terminals B. Endosomes, containing activated receptors, could be transported to the cell body of the neuron C. Dynein could be involved in regulating the activation of Trk receptors D. None of the above |
A. Dynein could be involved in transporting newly synthesized receptors to nerve terminals
|
|
|
52. The effectors proteins of G protein-coupled receptors produce the so-called second messenger molecules. What are the first messengers?
A. Hormones and neurotransmitters that act, via their receptors, on the G proteins. B. Precursor molecules, the enzymatic degradation of which produces the second messengers C. Subunits of the receptors that are involved in transducing the changes in receptor structure into a functional response D. None of the above |
A. Hormones and neurotransmitters that act, via their receptors, on the G proteins.
|
|
|
53. G proteins can be involved in regulating ion channels. They can do this by:
A. Activating effectors to produce second messengers which in turn activate kinases that phosphorylate the ion channel to change ion channel activity B. Activating effectors to produce second messengers which then act directly on ion channels to change ion channel activity C. Acting directly on the ion channel to change ion channel activity D. All of the above. |
D. All of the above.
|
|
|
54. The mechanism of action of neuropeptides is:
A. Usually through ion channel type receptors B. Highly versatile, utilizing G protein-coupled receptors ion channels receptors or tyrosine kinase receptors C. Through G protein-coupled receptors D. None of the above |
C. Through G protein-coupled receptors
|
|
|
55. In the ß-adrenergic receptor, the binding site for noradrenalin is:
A. Deep within the receptor, within the transmembrane regions B. In the large extracellular domain of the receptor C. In the region possessing a glycosyation, which is important in determining receptor specificity D. None of the above. |
A. Deep within the receptor, within the transmembrane regions
|
|
|
56. Which of the following interactions is not involved in noradrenalin binding to the ß-adrenergic receptor?
A. Covalent bonding B. Hydrogen bonding C. Ion paring D. Hydrophobic interactions |
A. Covalent bonding
|
|
|
57. The G protein binding domain of G protein-coupled receptors is found:
A. Deep within the receptor, within the transmembrane regions B. Within a subunit of the receptor, buried in the transmembrane region, that becomes exposed upon ligand binding C. Within intracellular loops of the receptor D. None of the above |
C. Within intracellular loops of the receptor
|
|
|
58. What is the significance for the fact that many serines and threonines are found within the
intracellular loops of G protein-coupled receptors? A. These amino acids can be phosphorylated by kinases and thus can function as part of regulatory domains B. These amino acids can form disulphide bridges with the G proteins and function as part of the G protein binding domain C. These amino acids can ion pair with acetic amino acids of the transmembrane regions, thus making an important contribution to the tertiary structure of the receptor D. None of the above |
A. These amino acids can be phosphorylated by kinases and thus can function as part of regulatory
domains |
|
|
59. What does glutamate, GABA and Ca2+ have in common?
A. They are all ligands for ion channel receptors B. They are all ligands for tyrosine kinase receptors C. They are all ligands for G protein-coupled receptors D. None of the above |
C. They are all ligands for G protein-coupled receptors
|
|
|
60. Large peptides or even proteins can be ligands for G protein-coupled receptors. In such cases the ligand-receptor interaction usually involves:
A. Cleavage of the protein to small peptides which then interact with the ligand-binding domain of the receptor B. Binding of the protein to a extracellular ligand-binding domain and then an interaction of a portion of the protein with the transmembrane region to effectuate signal transduction C. The C-terminal end of the protein binds with the ligand-binding domain which is deep within the transmembrane region D. None of the above |
B. Binding of the protein to a extracellular ligand-binding domain and then an interaction of a
portion of the protein with the transmembrane region to effectuate signal transduction |
|
|
61. G proteins are called G proteins because:
A. They are GTPases B. They possess high content of the amino acids glutamate and glycine C. They have binding sites for cyclic-GMP D. None of the above. |
A. They are GTPases
|
|
|
62. G protein-coupled receptors can be thought of as working like an enzyme because:
A. They have catalytic sites that resemble the catalytic site of tyrosine kinases. B. Similar to enzymes, they are regulated by ligand binding C. Once activated they can perform their function (activation of G proteins) many times before they become inactivated D. None of the above. |
C. Once activated they can perform their function (activation of G proteins) many times before
they become inactivated |
|
|
63. The G protein of a G protein-coupled receptor becomes activated when:
A. There is an exchange of GDP for GTP within the G protein, and the G protein complex dissociates B. GTP is hydrolyzed to GDP, thus exposing sites within the G protein that can bind to effector molecules C. The G protein becomes phosphorylated by an appropriate kinase, thereby inducing changes in G protein structure that allows it to bind to effector proteins D. None of the above. |
A. There is an exchange of GDP for GTP within the G protein, and the G protein complex dissociates
|
|
|
64. When acting upon a G protein the neuropeptide-receptor complex:
A. Activates the catalytic site of the GTPase B. Stimulates the binding of the activated G protein with its effector protein C. Facilitates the exchange of GDP for GTP D. None of the above. |
C. Facilitates the exchange of GDP for GTP
|
|
|
65. The beta/gamma subunit of a G protein, when dissociated from the trimeric G protein complex:
A. Has an autofeedback action on the activity of the alpha subunit B. Can regulate (stimulate or inhibit) its own effector proteins C. Is responsible for the hydrolysis of GTP to GDP D. Has no function |
B. Can regulate (stimulate or inhibit) its own effector proteins
|
|
|
66. The effector protein for the G protein aq is:
A. Phospholipase-Cß B. Phospholipase-C. C. Voltage-operated Ca2+ channels D. All of the above |
A. Phospholipase-Cß
|
|
|
67. The effector protein for the G protein ai is:
A. Adenylyl cyclase B. Phospholipase Cß C. Calcium calmodulin kinase II (CaMKII) D. All of the above |
A. Adenylyl cyclase
|
|
|
68. Alpha subunits of G proteins possess:
A. Higher target (effector) specificity than beta/gamma subunits B. Higher potencies than beta/gamma subunits (i.e. they are effective at lower concentrations) C. The catalytic site for GTP hydrolysis D. All of the above |
A. Higher target (effector) specificity than beta/gamma subunits
|
|
|
69. Cone opsins are essentially light sensitive G protein-coupled receptors, activated by light (rather than by e.g. a neuropeptide). What gives the opsins their different light absorbing properties?
A. Each opsin possesses a slightly different light-absorbing retinal molecule, thus accounting for their different light absorbing spectrums B. Each opsin associates with a slightly different G protein that ultimately determines the light absorbing properties of the opsin C. Each opsin has slightly different amino acid sequences that ultimately account for their different light absorbing properties D. All of the above |
C. Each opsin has slightly different amino acid sequences that ultimately account for their different
light absorbing properties |
|
|
70. The effector protein of rhodopsin is the enzyme phosphodiesterase. Activation of this enzyme leads to:
A. Lower levels of cyclic GMP in the rods, leading to hyperpolariatation of the rods in response to light B. Higher levels of cyclic GMP in the rods, and thus deperpolarization of the rods in response to light C. Phophorylation of diesterase bonds within kinases, with a consequent activation of intracellular signaling cascades by these kinases, leading to membrane depolarization D. None of the above. |
A. Lower levels of cyclic GMP in the rods, leading to hyperpolariatation of the rods in response to
light |
|
|
71. What is the function of cyclic GMP in sensory transduction by the rod cells of the retinal?
A. It activates protein kinase G (PKG), which in turn phosphorylates cation channels on the membrane of the rod cells, leading to membrane depolarization B. It activates protein kinase G (PKG), which in turn initiates an intracellular signaling cascade which ulitimately leads to phosphorylation cation channels on the membrane of the rod cells, leading to membrane depolarization C. It acts directly on cation channels on the membrane of the rod cells, leading to membrane depolarization D. None of the above |
C. It acts directly on cation channels on the membrane of the rod cells, leading to membrane
depolarization |
|
|
72. Cholera toxin and pertussis toxin act on G protein-coupled receptor signaling systems to exert their toxic effects. In their mechanism of action these toxins:
A. Act directly on the G proteins B. Act as receptor ligands to cause an inappropriate activation of the receptors C. Act directly on effector proteins of the G protein-coupled receptor signaling system D. None of the above |
A. Act directly on the G proteins
|
|
|
73. Cellular programs of cells reflect which enzymes are expressed by the cells. These enzymes often drive metabolic pathways. The role of hormones (and often neuropeptides) is to:
A. Regulate the activity of the enzymes, thus regulating the direction and speed of the metabolic pathways B. To create new pathways to increase the diversity of cellular programs within a given cell type C. Inhibit the enzymes, thus shutting down the pathways which in turn sends the cell into an inactive state D. None of the above |
A. Regulate the activity of the enzymes, thus regulating the direction and speed of the metabolic
pathways |
|
|
74. There are many isoforms of the enzyme adenylyl cyclase, all of which can be activated by GS. Some isoforms can are regulated by:
A. Gi B. Protein Kinase C (PKC) C. Protein Kinase A (PKA) D. All of the above |
D. All of the above
|
|
|
75. While Gi is usually associated with the inhibition of adenylyl cyclase, some forms of adenylyl cyclase are activated with the activation of Gi. This is because:
A. These forms of adenylyl cyclase are activated instead of inhibited by the αi subunit B. These forms of adenylyl cyclase are insensitive to αi and are stimulated by β/γ subunits produced by the dissociation of Gi C. Gi activates other effectors which then activate adenylyl cyclase in an indirect way D. None of the above |
C. Gi activates other effectors which then activate adenylyl cyclase in an indirect way
|
|
|
76. Some isoforms of adenylyl cyclase can function as coincidence detectors. This coincidence detection can concern:
A. A simultaneous stimulation of the cyclase by αs and αq subunits B. Concurrent stimulation of the cell by two neurotransmitters, one generating activated as subunits, the other generating a signal that ultimately lifts an inhibitory subunit from the cyclase C. Concurrent stimulation of the cell by two neurotransmitters, one generating activated as subunits, the other generating a strong β/γ signal D. None of the above |
C. Concurrent stimulation of the cell by two neurotransmitters, one generating activated as
subunits, the other generating a strong β/γ signal |
|
|
77. There are two forms of guanylyl cyclase, one the so-called soluble form and the other is called the particulate form. The soluble form is called soluble because:
A. In an ether extraction of the cells, it is found in the ether soluble fraction reflecting the fact that it is a very hydrophobic protein B. In an aqueous extraction of cells, it is found that following centrifugation the cyclase is in the soluble supernatant fraction C. Upon phosphorylation of the cyclase it converts from an insoluble to a soluble enzyme, and is thus in a state to produce cyclic GMP D. None of the above |
B. In an aqueous extraction of cells, it is found that following centrifugation the cyclase is in the
soluble supernatant fraction |
|
|
78. Both Atrial Natriuretic Peptide (ANP) and nitric oxide (NO) cause vasodilation and a lowering of blood pressure. They do this by:
A. Activating their G protein-coupled receptors, which in turn activate guanylyl cyclase B. Inducing the release of acetylcholine, that in turn causes vasodilation C. Activating their receptors, which are guanylyl cyclases D. None of the above |
C. Activating their receptors, which are guanylyl cyclases
|
|
|
79. Nitric oxide synthase (NOS) is a component of a signaling cascade that regulates vasodilation. This enzyme is regulated by:
A. The G protein Gq B. Protein kinse A (PKA) C. Ca2+ calmodulin kinase II (caMKII) D. None of the above |
C. Ca2+ calmodulin kinase II (caMKII)
|
|
|
80. Phospholipase Cβ is a lipase which:
A. Is the effector enzyme for the G protein Gq B. Degrades the phospholipid phosphtidyinositol 4,5 P2 C. Generates two intracellular second messengers D. All of the above |
D. All of the above
|
|
|
81. It is important that second messenger molecules have short half-lives. For the second messenger cyclic AMP there are:
A. High-affinity binding proteins for cyclic AMP in the cytoplasm for sequestering the cyclic nucleotide B. Phosphodiesterases in the cytoplasm for the conversion of cyclic AMP to AMP C. Kinases in the cytoplasm which phosphorylate cyclic AMP to an inactive form of the cyclic nucleotide D. All of the above. |
B. Phosphodiesterases in the cytoplasm for the conversion of cyclic AMP to AMP
|
|
|
82. It is important that second messenger molecules have short half-lives. For the second messenger inositol triphosphate (IP3) there are:
A. High-affinity binding proteins for IP3 in the cytoplasm for sequestering the second messenger molecule B. Transport mechanisms on the membrane to pump IP3 out of the cell C. Phosphatases in the cytoplasm for breaking down IP3 D. All of the above |
C. Phosphatases in the cytoplasm for breaking down IP3
|
|
|
83. In general protein kinase A (PKA) has a much greater working range that protein kinase G (PKG). This is because:
A. The catalytic domains of PKA come free from the regulatory domains and are free to diffuse throughout the cell whereas for PKG the regulatory and catalytic domains are within one large (and thus less diffusible) protein B. There are transport proteins specific for PKA which transport the activated kinase to different parts of the cell; PKG lacks any transport proteins C. PKG is usually anchored to the cytoskeleton whereas PKA is not D. All of the above |
A. The catalytic domains of PKA come free from the regulatory domains and are free to diffuse
throughout the cell whereas for PKG the regulatory and catalytic domains are within one large (and thus less diffusible) protein |
|
|
84. Phosphatidyl serine (PtdSer), Ca2+ and diacylglycerol (DAG) all have binding sites in the regulatory domain of protein kinase C (PKC), but DAG is considered the physiological regulatory of the enzyme. This is because:
A. Of these three ligands, only the levels of DAG are physiologically regulated in a cell B. PtdSer and Ca2+ are usually present at sufficiently high levels to support enzyme activity whereas DAG is not C. PtdSer and Ca2+ binding are not required for enzyme activity, whereas binding of DAG binding is obligatory for enzyme activity D. None of the above |
B. PtdSer and Ca2+ are usually present at sufficiently high levels to support enzyme activity whereas
DAG is not |
|
|
85. The protein calmodulin is:
A. Present at high concentration in every cell B. A Ca2+ binding protein that undergoes a structural change upon Ca2+ binding C. Highly conserved D. All of the above |
D. All of the above
|
|
|
86. Ca2+ calmodulin kinase II (CaMKII) is considered a kinase with a “memory” because:
A. Once it is activated it is locked into the active state by a regulatory subunit B. It undergoes an irreversible conformation change upon binding Ca2+-calmodulin C. It can transphosphorylate itself, thereby putting the enzyme in Ca2+ independent active state D. None of the above |
C. It can transphosphorylate itself, thereby putting the enzyme in Ca2+ independent active state
|
|
|
87. In a dopaminergic nerve terminal a Ca2+ microdomain can induce exocytosis and activate Ca2+ calmodulin kinase (CaMK). The CaMK can in turn:
A. Regulate the activity of thyrosine hydroxylase B. Phosphorylate the protein synapsin 1 C. Regulate dopamine pumps on the membrane of secretory granules D. All of the above |
D. All of the above
|
|
|
88. Ca2+ calmodulin kinase II (CaMKII) often occurs in a complex containing 12 CaMKII molecules. The functional importance of this complex formation is:
A. To increase the probability of transmolecular phosphorylation, and thus aid the functioning of CaMKII as a “memory”molecule B. To form an efficient centralized site for phosphorylation within a cell C. To form a platform to be used as a scaffold for organizing proteins involved in intracellular signaling cascades D. All of the above |
A. To increase the probability of transmolecular phosphorylation, and thus aid the functioning of
CaMKII as a “memory”molecule |
|
|
89. Ca2+ calmodulin kinase II (CaMKII) can exist as a monomer or as complex containing 12 CaMKII molecules. Which form a cell possesses depends on:
A. Whether the enzyme system responsible for the construction of the complex is expressed in the cell or not B. Whether the CaMKII isoform expressed by the cell possesses the “self-association” domain or not C. Whether the Ca2+ signaling cascade responsible for complex formation has been activated or not D. None of the above |
B. Whether the CaMKII isoform expressed by the cell possesses the “self-association” domain or
not |
|
|
90. G protein-coupled receptor mechanisms have been termed “metabotropic” because the
phosphorylations they induce (via activation of kinases) can affect the metabolism of a cell. The consequences can last for many days (or even years) because: A. Phosphorylations are almost irreversible, and thus the changes introduced remain for very long times B. The proteins phosphorylated by G protein signaling cascades can be transcription factors which bring about changes in gene expression and thus long term changes to the cell C. Changes in cell metabolism are almost always irreversible D. None of the above |
B. The proteins phosphorylated by G protein signaling cascades can be transcription factors which
bring about changes in gene expression and thus long term changes to the cell |
|
|
91. A kinase anchoring proteins (AKAPs) can be involved in constructing supramolecular signaling complexes. They are called AKAPs because:
A. They bind exclusively various isoforms of protein kinase A (PKA) B. They not only bind PKA but they also possess cyclic AMP binding sites to anchor the cyclic nucleotide close to the kinase C. They all bind PKA (and many can bind other proteins such as other kinases and/or phosphatases) D. None of the above |
C. They all bind PKA (and many can bind other proteins such as other kinases and/or
phosphatases) |
|
|
92. The constraints of signaling domains on the membrane can add to the versatility of the G protein coupled receptor mechanisms to generate diverse signals. This is because:
A. The cell, through the construction of domains with different receptors and G proteins, can control what its (unambiguous) response will be to activation by particular receptor mechanisms B. The signaling domains allow a cell to keep phosphatases compartmentalized from kinases and thus avoids interactions between these two classes of signaling proteins C. The signaling domains provide a site for downstream signaling components, such as the kinases, to insert themselves into the membrane, thus becoming part of the signaling complex D. All of the above |
D. All of the above
|
|
|
93. The transcription factor CREB received its name for the fact that it can be activated by cyclic-AMP signaling pathways (Cyclic AMP Responsive Element Binding protein). This transcription factor:
A. Is, as it’s name implies, exclusively activated by cyclic-AMP signaling pathways B. Is also a target for Calcium-calmodulin kinase II (CaMKII) and MAP Kinase signaling cascades C. Acts directly on the transcriptional machinery following its binding to CRE D. None of the above |
C. Acts directly on the transcriptional machinery following its binding to CRE
|
|
|
94. DREAM is a transcription factor which suppresses gene expression. Its binding to its downstream responsive element is lifted through:
A. A Ca2+-calmodulin kinase (CaMK) dependent phosphorylation of the factor B. Ca2+ -calmodulin binding to the factor C. Ca2+ binding directly to the factor D. None of the above |
C. Ca2+ binding directly to the factor
|
|
|
95. C-fos is an immediate early gene. The “c-fos method” is based on the premise that:
A. This immediate early gene come to expression in cells that were just activated and that this expression is transitory (thus showing a positive signal in cells that have just been activated) B. Factors that affect c-fos expression also affect expression of late genes, thus the late genes act as a marker for c-fos expression C. Late genes code for factors which have a negative feedback effect on c-fos expression, thus inhibition of c-fos expression indicate late gene expression D. All of the above |
A. This immediate early gene come to expression in cells that were just activated and that this
expression is transitory (thus showing a positive signal in cells that have just been activated) |
|
|
96. There are binding proteins in the blood for most steroid hormones. The function of these binding proteins might be to:
A. Aid in the release of the hormone from the steroid producing endocrine cells B. Protect the steroid from degradation in the liver C. Play a role in determining what level of “unbound” steroid is available for target cells D. All of the above |
D. All of the above
|
|
|
97. The enzyme cholesterol ester hydrolase (CEH) is the rate-limiting enzyme for the production of steroid hormones. For glucocorticoid production in the adrenal gland this enzyme is regulated by:
A. A signaling cascade involving protein kinase A (PKA) phosphorylation which activates CEH B. A signaling cascade involving activation of phosphatases, which dephosphorylate and thus activate CEH C. A signaling cascade involving phosphodiesterase activation of CEH D. None of the above |
A. A signaling cascade involving protein kinase A (PKA) phosphorylation which activates CEH
|
|
|
98. The glucocorticoid receptor is a transcription factor. This transcription factor can:
A. Bind to glucocorticoid responsive elements (GRE) to promote gene expression B. Bind to negative glucocorticoid responsive elements (nGRE) to repress gene gexpression C. Bind to and interfere with other transcription factors to inhibit gene expression D. All of the above |
A. Bind to glucocorticoid responsive elements (GRE) to promote gene expression
|
|
|
99. The synthesis and release of glucocorticoids, sex steroids and thyroxine are all regulated by factors (hormones) released from the pituitary gland. The production and release of the pituitary factors can be regulated by feedback loops. These feedback loops:
A. Are only negative in nature because positive feedback would lead to unstable conditions B. Are effectuated only through action on negative responsive elements of genes C. Can be directed to the hypothalamus or to the pituitary gland (or to both) D. All of the above |
A. Are only negative in nature because positive feedback would lead to unstable conditions
|
