Biology/ANNB 261 Exam 2 Spring, 2006 Name

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1 Biology/ANNB 261 Exam 2 Spring, 2006 Name Multiple Choice: 1. are responsible for phosphorylation of receptor proteins, whereas are responsible for dephosphorylation of receptor proteins. a) Kinases; phosphatases* b) Phosphatases; kinases c) Second messengers; ligands d) Ligands; second messengers e) Kinases; second messengers 2. Which of the following is NOT a second messenger in the PIP 2 signaling cascade? a) IP 3 b) DAG c) camp* d) Ca Activation of a G-protein-coupled receptor by a neurotransmitter causes an increase in inositol-1,4,5-triphosphate (IP 3 ) levels inside the cell. Which of the following typically happens next? a) IP 3 would be broken down into DAG and PIP 2 b) IP 3 would activate PKC c) IP 3 would cause the release of Ca 2+ from the endoplasmic reticulum* d) IP 3 would bind to and activate a K + channel e) IP 3 would activate a Ca 2+ -binding protein that results in a down regulation of DAG 4. You discover bowenamine and believe that it is a neurotransmitter. You have proved that it is released from the neuron upon stimulation and that it is degraded in the synaptic cleft. What else do you need to prove in order to convince your neuroscientist colleagues that bowenamine is a neurotransmitter? a) Bowenamine is a phosphorylated protein b) Bowenamine is synthesized and stored in the presynaptic cell c) Bowenamine causes a response in the postsynaptic neuron d) Bowenamine is transported back into the presynaptic membrane d) Both b and c* Accepted D or E because original test did not have an e option (last two were labeled d). 5. 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

2 e) More than one of the above is correct 6. 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* I accepted all answers for question 7. A term was omitted and all answers were potentially correct. 7. 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) Increase in the amount of intracellular IP 3 8. 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; Cl - 9. 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 10. Which of the following is NOT a primary taste? a) Salt b) Sour c) Protein* d) Sweet

3 11. 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) open a chloride channel e) close a potassium channel* 12. 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 13. 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 T1R1+T1R3 heterodimer G-protein coupled receptor* c) A T2R3+T2R1 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 14. Olfactory transduction involves which of the following? a) G olf G-protein coupled to an odor receptor b) Binding of adenylate cyclase to a Ca 2+ channel* c) An odor activated Cl - channel d) Ca 2+ binding proteins 15. Termination of olfactory transduction involves which of the following? a) Ca 2+ binding proteins b) Blocking of a nucleotide-gated Na + and Ca 2+ channel c) A Na + /Ca 2+ exchange channel d) Activation of a Cl - channel that hyperpolarizes the cell membrane e) A, b, and c but not d* 16. 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

4 17. 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 18. 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 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* 19. 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 20. Preganglionic fibers in the sympathetic nervous system use for a neurotransmitter. a) Epinephrine b) Norepinephrine c) Acetylcholine (Ach)* d) Glutamate e) Serotonin 21. 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) angiotensin c) anti-diuretic hormone* d) oxytocin e) corticotrophin-releasing hormone

5 22. 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 which use ACh 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 located close to their target organs. These neurons use norepinephrine as a neurotransmitter. c) It has short preganglionic axons that synapse in a chain of ganglia located close to the spinal cord. These neurons use ACh as their neurotransmitter. * d) It has short preganglionic axons that synapse in a chain of ganglia located close to their target organs. Postsynaptic neurons use norepinephrine as their neurotransmitter. e) It has long preganglionic axons that synapse in a chain of ganglia located close to their target organs. Postsynaptic neurons use norepinephrine as their neurotransmitter. 23. 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* 24. The thinnest part of the retina, where visual acuity is at its highest, is called the a) Fovea* b) Macula c) Optic disk d) Conjunctiva e) Sclera 25. Many adults lose the ability to effectively contract the lens as they age. This leads to a condition known as a) Hyperopia b) Myopia c) Emmetropia d) Presbyopia* e) Strabismus 26. Why is the fovea best suited for high visual acuity? a) There are fewer photoreceptors providing input to any particular ganglion cell b) The neuronal retinal layers are displaced laterally c) There are more cones in the fovea d) The receptive fields of cones are smaller and thus better able to respond to small details e) All of the above*

6 27. At rest (in the dark), there is a concentration of cyclic guanosine monophosphate (cgmp) in the outer segments of photoreceptors, causing cgmp-gated sodium channels to be in a(n) state. a) Higher; open* b) Higher; closed c) Lower; open d) Lower; closed because it is actually a cgmp-gated potassium channel. 28. You are walking along during a bright, sunny day when your friend shines a flashlight into your eye. What effect would the added light have on your rods? a) It would cause the rods to depolarize b) It would not cause any change in the rods membrane potential* c) It would cause the rods to hyperpolarize d) The rods membrane potential will gradually depolarize over several minutes as the eye adapts e) The change in membrane potential cannot be determined 29. How is phototransduction in cones different from that in rods? a) Cones have different forms of transducin b) Cones have different forms of opsins* c) Cones substitute phosphodiesterase with guanylate synthase d) Sodium channels in cones close in response to light, while rod channels open in response to light e) Retinal arrestin is down-regulated in rods but not cones. 30. How is color vision (at the receptors of the retina) best described? a) Colors are seen by the selective firing of red, green, and blue cones (i.e., only red cones fire in response to red light) b) Colors are seen by comparing the contribution of rods to the contribution of cones in vision c) Colors are seen by activation of specific regions of the retina d) Colors are seen by comparing the relative contributions of red, green, and blue cones in response to light* e) Colors are seen by rods and cones providing signals for lateral interactions between amacrine cells and receptors organized in receptive fields 31. OFF bipolar cells use and in response to glutamate release. a) G-protein-coupled receptors; depolarize b) G-protein-coupled receptors; hyperpolarize c) Glutamate-gated ion channels; depolarize* d) Glutamate-gated ion channels; hyperpolarize e) GABA-gated ion channels; hyperpolarize

7 32. Which stimulus would maximally excite an OFF-center ganglion cell with an antagonistic surround? a) A dark spot in the surround b) A light spot in the surround c) A light spot in the center d) A combination of light covering the surround and dark in the center* e) A combination of dark covering the surround and light in the center 33. Which of the following are true for M cells? a) They are important for the detection of stimulus movement* b) They are more sensitive to high-contrast stimuli than are P cells c) They have slowly conducting axons d) They respond to color stimuli e) They respond to stimuli in the receptive field center with a sustained discharge of action potentials 34. Green ON-center ganglion cells always have yellow OFF surrounds. Which photoreceptors would most likely contribute to this antagonistic yellow surround? a) Red and blue cones b) Red and green cones* c) Green and blue cones d) Red, green and blue cones e) Rods and blue cones 35. If all the ganglion cells in your left temporal retina were destroyed, a) You could not see things in your right visual field b) You could not see things in the monocular zone of your right visual field* c) You could not see things in the monocular zone of your left visual field d) You could not see anything in the middle central portion of the right visual field 36. M-type ganglion cells, compared with P-type ganglion cells, a) Have a smaller dendritic field b) Respond to color differences c) Have a larger receptive field* d) Respond to images projected directly onto the fovea is correct

8 Briefly define or describe 3 of the following 5 (4 points each): Name a. Pheromone: olfactory stimulus used for chemical communications between conspecifics (reproduction, mate selection, emotional state) 38. Glomerulus: location where olfactory receptor neurons expressing the SAME receptor synapse with cells of olfactory bulb. It is marked by many synaptic connections between rich branching of terminal and dendrites. 39. calcium-calmodulin-dependent protein kinase (CaMK): a protein kinase activated by elevations of internal Ca2+ concentrations. It can phosphorylate a protein channel. May be activated by calcium released by the IP3 second messenger pathway. 40. striate cortex: primary visual cortex (area 17; V1) where most visual sensory input first arrives at the cortex for processing. a. negative afterimage: image that occurs after a prolonged visual stimulus is removed. In color vision, red or green afterimage will be seen after simulation of green or red, respectively. Blue and yellow also form opposite afterimages. Used as early evidence of color-opponent processes. b. Essay (15 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-Daspartate) receptors are two of the superfamily of glutamate receptors. Both receptors are ligand binding, ionotropic, and allow Na+ and K+. NMDA also has a Ca2+ current. AMPA receptor has a fast, short-duration EPSP. NMDA has a voltage-dependent current and does not produce much of an EPSP current at Vm of 65 mv because Mg2+ blocks the channel. If Vm is depolarized the inward current (Na+) increases, peaking between 40 and 20 mv. I R occurs at about 0 mv with outward (K+) current increasing at higher Vm. Having the two channels together in the same synapse has the advantage that molecules neurotransmitter (Glu) can bind to both types of receptors at the same time. The EPSP from activation of AMPA will depolarize the membrane, dislodging the Mg2+ from the NMDA receptor,. The resulting EPSP from the NMDA receptor can be much longer lasting.