Download Biology/ANNB 261 Exam 2

Neurobiology 261 Exam 2
Fall, 2006
Name_________________________
Multiple Choice:
1.
a)
b)
c)
d)
e)
The molecule that catalyzes the conversion of ATP to cAMP is
Phospholipase C
Adenylyl cyclase*
Endonuclease
Protein kinase
G-coupled protein
2.
a)
b)
c)
d)
e)
Which of the following are best at dephosphorylating a transmembrane channel protein?
Phosphatases*
Kinases
Dephosphorylases
Neurotransmitters
None of the above
3.
a)
b)
c)
d)
e)
How could you increase the length constant of a dendrite?
Open up potassium channels in the membrane of the dendrite
Close potassium channels in the membrane of the dendrite*
Open chloride channels in the membrane of the dendrite
Change the density of voltage-activated sodium gates at each branch of a dendrite
Decrease the diameter of the dendrite
4.
a)
b)
b)
c)
d)
Neurons often use protein kinases to
Dephosphorylate proteins
Phosphorylate proteins*
Form cAMP
Bind neurotransmitter
Deactivate G-coupled protein subunits
5.
a)
b)
c)
d)
e)
The IA current differs from the IK current in that
IA is a calcium current rather than a potassium current
IA is activated after the IK current
IA has a longer duration than IK when the membrane remains depolarized
Compared to IK, IA adds only modestly to repolarization during the relative refractory period
IA hyperpolarizes the membrane before the action potential rather than after*
6.
a)
b)
c)
d)
e)
Increasing the intracellular concentration of calcium in a neuron will
Increase the driving force for calcium at resting membrane potential
Increase the equilibrium potential for calcium
Increase phosphorylation of synapsin*
Decrease the resting membrane potential of the neuron
A and B are correct
7. An important characteristic of the IM current is that
a) It is based on a Ca2+ activated channel
b) It hyperpolarizes the membrane before the action potential, slowing the onset of the action
potential
c) It is a short-duration current because of an inactivation gate
d) It decreases the duration of the action potential
e) It can be regulated by synaptic transmitter activity*
8. No correct answer. Everyone got 2 points
9.
a)
b)
c)
d)
e)
A cell that uses norepinephrine as a neurotransmitter also contains
dopamine*
epinephrine
serotonin
“vagusstoff”
glutamine
10. Which of the following is NOT a second messenger in the PIP2 signaling cascade?
a. IP3
b. DAG
c. cAMP *
d. Ca2+
e. None of the above
11. Activation of a G-protein-coupled receptor by a neurotransmitter causes an increase in
inositol-1,4,5-triphosphate (IP3) levels inside the cell. Which of the following typically
happens next?
a) IP3 would be broken down into DAG and PIP2
b) IP3 would activate PKC
c) IP3 would cause the release of Ca2+ from the endoplasmic reticulum *
d) IP3 would bind to and activate a K+ channel
e) IP3 would activate a Ca2+-binding protein that results in a down regulation of DAG
12. The precursor for gamma-aminobutyric acid is _________?
a) tryptophan hydroxylase
b) glutamate*
c) L-dihydroxyphenylalanine
d) choline acetyltransferase
e) glutamic acid decarboxylase
13. You are studying a class of neurons and discover that these neurons release dopamine into the
synaptic cleft. Based on this information, you can conclude that these neurons
a) Contain tyrosine hydroxylase in their somas but not in their terminals
b) Contain tyrosine hydroxylase in their axon terminals*
c) Contain norepinephrine in their axon terminals
d) Contain dopamine β-hydroxylase in their axon terminals
e) B and D are correct
14. What must be done to terminate G-protein-coupled receptor-mediated signaling?
a) Neurotransmitter must be removed from the synaptic cleft
b) G-proteins must be inactivated, and second messengers must be degraded
c) Proteins must be dephosphorylated
d) Neurotransmitter must be removed from the receptor binding site
e) All of the above*
15. Cholera is a disease that prevents the breakdown of GTP bound to G-proteins, resulting in a
constitutively active α subunit. Stimulation of a neuron infected with cholera could lead to
a) Decreased PKA activity
b) Inhibition of adenylate cyclase
c) Decreased levels of phosphorylated protein in the neuron
d) Increased amounts of cAMP*
e) Decrease in the amount of intracellular IP3
16. VX poison gas is a potent inhibitor of acetylcholinesterase, the enzyme responsible for
degrading acetylcholine at the synapse. Stimulating a synapse with ACh-gated ion channels in
the presence of VX will cause a ______________ concentration of ACh in the synapse, with
the initial effect of increasing the amount of ______________ passing through the
postsynaptic membrane.
a) Greater; Na+ *
b) Greater; K+
c) Lesser; Na+
d) Lesser; K+
e) Greater; Cl17. In normal neurons, even though glutamate is called an excitatory neurotransmitter, when it
binds to NMDA receptors, Vm of the postsynaptic membrane may change very little. This is
likely due to the presence of
a) Glutamic acid decarboxylase
b) Glutamine synthetase
c) Excitatory amino acid transporters
d) Magnesium ions
e) AMPA receptors
18. Which of the following is NOT a primary taste?
a) Salt
b) Sour
c) Protein
d) Sweet
e) None of the above
19. Acid stimuli and NaCl can be detected by common mechanisms, but sour transduction can also
__________ which is not involved in NaCl transduction.
a) activate an action potential
b) activate a G-protein (gustducin)
c) activate amiloride-sensitive channels
d) close a potassium channel *
e) open a chloride channel
20. You are recording from a single fiber of the facial nerve (CN VII) and you believe that you are
recording from an “S best” neuron. This means that the neuron’s action potentials are probably
encoding information about
a) sodium chloride
b) sucrose *
c) sour
d) quinine
e) salt
21. The taste of amino acids is thought to be detected by which of the following receptor?
a) A T1R2+T1R3 heterodimer G-protein coupled receptor
b) A T2R3+T2R1 heterodimer G-protein coupled receptor
c) A T1R1+T1R3 heterodimer G-protein coupled receptor *
d) A leak channel that causes an action potential
e) An ionotropic channel that is selective for the amino acid
22. Olfactory transduction involves which of the following?
a) Golf G-protein coupled to an odor receptor *
b) Binding of adenylate cyclase to a Ca2+ channel
c) An odor activated Cl- channel
d) Ca2+ binding proteins
e) None of the above
a) No correct answer: Everyone got 2 points
23. The central nervous system pathway most likely to be involved in the identification of a
specific odor
a) olfactory bulb – olfactory tubercle – piriform cortex - entorhinal cortex
b) olfactory bulb – perforate cortex - entorhinal cortex – piriform cortex
c) olfactory tract – tufted cell – temporal cortex
d) olfactory bulb- olfactory tubercle – dorsal medial n. of thalamus – orbitofrontal cortex *
e) olfactory tract - olfactory tubercle – contralateral olfactory bulb
25. The difference between sensory adaptation and habituation is adaptation occurs _______ and
habituation occurs _______.
a) In a receptor cell; in a neuron *
b) In a neuron; in a receptor
c) In an interneuron; in a receptor
d) In a receptor; in an interneuron
e) At the level of amacrine cells; at the level of horizontal cells
26. Which of the following is the most likely general quality that every sensory system encodes
within the action potential pattern sent to the brain?
a) Stimulus intensity
b) Duration of the stimulus
c) Unique stimulus qualities that can be described by the “Law of Specific Nerve Energies”
d) Topographical information about the location of a stimulus
e) All of the above *
27. Neurons in the locus coeruleus
a) Use norepinephrine as a neurotransmitter *
b) Use acetylcholine as a neurotransmitter
c) Use dopamine as a neurotransmitter
d) Use serotonin as a neurotransmitter
e) None of the above
28. Preganglionic fibers in the sympathetic nervous system use ________ for a neurotransmitter.
a) Epinephrine
b) Norepinephrine
c) Acetylcholine (ACh) *
d) Glutamate
e) Serotonin
29. You just returned from a long trip into the dessert and you did not have nearly as much water
as you needed. Because you lost water from your body, your hypothalamus released ________
to prevent your kidneys from producing more urine.
a) renin
b) anti-diuretic hormone *
c) angiotensin
d) oxytocin
e) corticotrophin-releasing hormone
30. Anatomical differences between the sympathetic and parasympathetic divisions of the ANS
enable the two systems to affect behavior in quite different manners. For example, the two
“effector” neurons (a disynaptic system) in each system are organized quite differently. Which
of the following statements regarding the sympathetic system is completely true?
a) It has short preganglionic axons that use adrenaline as their neurotransmitter, which makes it
possible for the adrenal medulla to enhance their effects
b) It has short preganglionic axons that synapse in a chain of ganglia close to their target organs.
c) Sympathetic neurons synapse close their target organs, giving them the ability to activate each
target organ independently of other organs.
d) Sympathetic neurons have short preganglionic axons that synapse in a chain of ganglia located
close to the spinal cord. *
e) It has long preganglionic axons that synapse in a chain of ganglia close to their target organs.
31. Repeat of question 28: Everyone got 2 points
32. The anatomy and functions of the diffuse modulatory neurotransmitter system differs from
synaptic communication systems in that diffuse systems ____________ whereas synaptic
systems ______.
a) are defined by the neurotransmitter; defined by the neurotransmitter receptor
b) influence neurons for long periods of time; influence neurons for only milliseconds
c) maintain brain homeostasis; alter brain function by point-to-point effects
d) B and C are true but not A
e) A, B and C are true *
33. A drop in the level of dopamine may be related to cell lose in which structure?
a) Raphe nucleus
b) Locus coeruleus
c) Basal forebrain complex
d) Substantia nigra *
e) All of the above
34. If you shine a light in one eye, which of the following will happen?
a) The pupil the light was shone into will contract
b) The pupil the light was not shone into will contract
c) The pupil the light was shone into will dilate
d) The iris of the opposite eye will get larger
e) A and B are true *
35. The ability of the lens to change shape gives the eye extra focusing power, a process called
a) Accommodation*
b) Reflection
c) Interpretation
d) Myopia
e) Hyperopia
Briefly define or describe 4 of the following 6 (4 points each): Name __________________
36. Pheromone (pg 264): An olfactory stimulus used for chemical communications between
individuals. May be important signals for reproductive behaviors, territorial marking,
identification, submission or aggression.
37. Glomerulus: spherical structure within the olfactory bulb where terminals of olfactory
receptor neurons (all expressing the same olfactory receptors) synapse with dendrites of about 100
second order olfactory neurons (mitral cells).
38. role of IP3 in olfaction (Travis’s lecture): IP3 binds to an IP3-gated calcium channel. This
opens the channel and increases Ca2+ in cytosol. This can lead to excitation and AP in
invertebrate, but modulates (either excites – calcium activated Cl- channel, or inhibits – e.g.,
calmodulin pathway) olfactory receptor neurons in mammals.
39. enteric division (pp 495-496): division of the autonomic nervous system embedded in the
lining of several gastrointestinal organs. Sensory neurons monitor tension and stretch of intestinal
walls, chemical status of stomach and intenstinal contents, hormonal levels in blood. Motor
control of smooth muscle motility, production of mucous and digestive secretions, diameter of
local blood vessels.
40. vesicular transporter: mechanism for moving either neurotransmitter molecules into a vesicle
against the concentration gradient (high concentration of NT on inside vesicle), or to move the
precursors to a neurotransmitter into a vesicle where they are assembled into the NT and stored
until exocytosis.
41. Reversal potential (pg 120): Vm at which the direction of current flow through a channel
reverses. ER is equal to Eion if channel is permeable to only one ion. It is between the Eions if
channel is permeable to more than one ion.
42. (15 points) You are on a hike and discover a novel fruit. Deciding to try it, you bite into the fruit.
It has a strong bitter aftertaste that makes you think that it activated a second messenger system
and naturally reminds you of a bitter transduction pathway you learned for this class. Diagram the
Bitter pathway activated by the β/δ subunits of Gustducin.
T2R receptors
↓
Gustducin G-coupled protein
↓
↑Beta/gamma complex
↓
↑Phospholipase C
PIP2 (phosphoatidylinositol-4,5-bisphosphate)
↓
↑IP3 (inositol triphosphate)
↓
↑Ca2+ (sER)
↓
↑TRPM5 channel activated (channel is a protein)
↓
↑Depolarization/Ca2+ (transient receptor potential)
↓
↑Exocytosis: ATP??
43. Essay (20 points):AMPA and NMDA receptors are often found together on the post synaptic
membrane. Compare and contrast the characteristics of each receptor. What is the advantage for a
neuron to have these two receptors next to each other (use the back of the page if necessary)?
AMPA (α-amino-3-hydroxyl-5-methyl-4-isoxazole-proionate) and NMDA (N-methyl-D-aspartate)
receptors are two members of the superfamily of glutamate receptors. Both receptors are ligand
binding, ionotropic, and selective for Na+ and K+. NMDA also has a Ca2+ current. AMPA
receptor produces a fast, short-duration EPSP. (AMPA receptors are NOT voltage-dependent)
NMDA has a voltage-dependent current and does not produce much of an EPSP current at a Vm
of –65 mV because Mg2+ blocks the channel. If Vm is depolarized, the inward current (Na+)
increases, peaking between –40 and –20 mV. Reversal potential occurs at about 0 mV with
outward (K+) current increasing as the inward Na+ current decreases (weakens) at higher Vm.
Having the two channels together in the same synapse has the advantage that molecules of the
same neurotransmitter (Glu) can bind to both types of receptors at the same time. The EPSP from
activation of AMPA will depolarize the membrane. This depolarization dislodges the Mg2+ from
the NMDA receptor. The resulting EPSP from the now open NMDA receptor may be slower to
develop but can be much longer lasting.