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Nsci 4100: Development of the Nervous System
2016 Examination 2
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Class 17 & 18 cell migration
1. Which of the following molecules is NOT a component of the extracellular matrix (ECM)?
A. collagen type IX
B. versican (a CSPG)
C. laminin

D. N-cadherin
E. All of the above are ECM components.
2. Which of the following statements is true regarding development of the neural crest (NC)?
A. NC cells are initially in the lateral margin of the neural plate.
B. NC cells migrate from the surface ectoderm into the mesoderm.
C. NC cells are transiently present in the dorsal neural tube.
D. NC cells develop from mesoderm.
AC E. More than one of the above are correct.
3. Several integrins are receptors for which of the following molecules?
A. slit
B. some semaphorins
C. ephrinAs

D. laminin
E. More than one of the above are correct.
4. Neural crest cells are described as undergoing an epithelial-to-mesenchymal transformation.
Which of the following are involved in this process?
A. Up regulation of expression of the transcription factors Snail and Slug.
B. Down regulation of expression of several integrins.
C. Up regulation of expression of ADAM proteases.
D. Down regulation of expression of N-cadherin.
ACD E. More than one of the above are correct.
5. In developing cerebellum, postmitotic neurons migrate …
A. tangentially from the medulla.
B. radially from the pial surface towards the ventricular surface.
C. radially from the ventricular surface towards the pial surface.
BC D. More than one of the above are correct.
6. Knockout of which single gene is likely to give a phenotype similar to that of a knockout of
the reelin gene?
A. Vldlr

B. Dab1
C. ApoEr2
D. Connexin43
E. More than one of the above are correct.
Nsci 4100 – Midterm Exam 2
page 2
7. Cells that migrate from ventral forebrain into neocortex during development are thought to
differentiate into what cell type?

A. neurons that use GABA as their neurotransmitter
B. neurons that use glutamate as their neurotransmitter
C. astrocytes
D. Cajal-Retzius cells
E. More than one of the above are correct.
8. The very first neurons to become postmitotic in the neocortex are found in what layer of the
adult cortex?

A. I
B. II/III
C. IV
D. V
E. VI
Class 19 research from Gammill
9. Which of the following is NOT a true statement about chick neural crest development?
A. Morpholinos can be electroporated to knock down target protein expression in neural
crest cells.
B. Neural crest cells are induced by cell-cell signaling.
C. Abnormal neural crest development can cause birth defects of the face and heart.

D. Neural crest cells give rise only to neural cells.
E. Neural crest migration has morphological and molecular similarities to cancer
metastasis.
Class 20 cell movement
10. In cell migration, the initial protrusion of a filopodia at the leading edge of the cell is due to
polymerization of …

A. actin.
B. myosin.
C. neurofilament.
D. tubulin.
E. More than one of the above are correct.
11. The shape of a neuron is largely determined by which component of the cytoskeleton?
A. actin filament
B. myosin filaments
C. neurofilaments

D. microtubules
12. Kinesin moves a cargo towards …
A. the minus end of a microtubule.

B. the plus end of a microtubule.
C. the minus end of an actin filament.
D. the plus end of an actin filament.
E. More than one of the above are correct.
Nsci 4100 – Midterm Exam 2
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13. During migration of immature cortical neurons, what is the first major cell organelle to be
moved into the leading process of the cell?
A. nucleus
B. golgi apparatus

C. centrosome
D. lysosome
E. mitochondria
14. Only 50% of the actin in a developing neuron is in filaments, yet the intracellular
concentration of free actin is above the concentration needed for polymerization. Why isn’t
more actin in filaments?
A. Much of the free actin is sequestered by myosin.
B. Polymerization of actin requires GTP, which is in limited supply.

C. Actin polymerization is regulated by actin binding proteins including Arp2/3 and
ADF/cofilin.
D. Actin polymerase is needed to make actin filaments, and this enzyme requires
energy to function.
E. More than one of the above are correct.
Class 21 neurite initiation
15. Which of the following is true regarding a typical postmitotic migrating projection neuron in
the developing neocortex, such as a pyramidal neuron?
A. The cell mainly uses axons growing in from the thalamus for its adhesive substrate.

B. The trailing process of the migrating cell will become the axon.
C. The trailing process of the migrating cell will become the dendrite.
D. The cell stops migrating as soon as it enters the cortical plate.
E. More than one of the above are correct.
16. Microtubule associated proteins (MAPs) …
A. sever microtubules.
B. stabilize microtubules.
C. cause microtubules to branch.
D. attach actin filaments to microtubules.
ABD E. More than one of the above are correct.
17. Catenins link ______________ to actin filaments. (Fill in the blank.)
A. integrins
B. Ig-CAMS

C. cadherins
D. microtubules
E. More than one of the above are correct.
18. Dynein …
A. can slide the plus end of microtubules into filopodia.
B. can walk a cargo towards the minus end of a microtubule.
C. forms a network just inside the cell membrane.
D. forms a network on the outside surface of the cell membrane.
AB E. More than one of the above are correct.
Nsci 4100 – Midterm Exam 2
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19. A filopodia extended from the leading edge of axonal growth cone can promote advance of
the growth cone if …
A. it adheres to an appropriate substrate molecule.
B. its network of actin filaments breaks down.
C. microtubules extend into it.
D. intermediate filaments polymerize within it.
AC E. More than one of the above are correct.
Class 22-23 axon guidance
20. Some neurons in the dorsal horn of the spinal cord send axons across the midline that then
ascend and synapse in the brain. Which of the following statements is true regarding the
growth of these axons during development?
A. They are repelled by factors released by floor plate cells in the spinal cord.
B. They are attracted by factors released by floor plate cells in the spinal cord
C. They grow towards the brain because they are repelled by Wnt4 that is expressed at
higher concentration in more caudal spinal cord.
D. They are attracted to the brain by the high level of Shh expressed in the brain.
AB E. More than one of the above are correct.
21. Treating neurons with growing axons in tissue culture with the drug cytochalasin B prevents
further actin polymerization. What immediate effect is this drug likely to have on the growing
axons?
A. The growth cones will advance at an accelerated rate.
B. The growth cones will retract.

C. The axons will continue to extend, but the growth cones will not respond to an
attractive or repulsive guidance cue.
D. The axons will continue to extend, but the growth cones will turn away from a
guidance cue that normally attracts them.
22. The majority of axons growing in the developing vertebrate central nervous system are
guided by adhesion to other axons. True or false?

A. true
B. false
23. Motor neurons in the lateral motor column (LMC) of the ventral horn of the sacral spinal cord
innervate the leg muscles. Neurons in the LMCl normally send axons to dorsal leg muscles,
and neurons in the LMCm send axons to the ventral leg muscles. Which of the following
statements is true regarding the guidance of LMC axons as they grow into the limb?

A. Axons destined for the dorsal limb expressing EphAs are repelled by ephrinAs in the
ventral limb.
B. Axons destined for the ventral limb expressing ephrinAs are repelled by EphAs in the
dorsal limb.
C. Axons destined for the dorsal limb expressing EphAs are attracted by ephrinAs in the
dorsal limb.
D. Axons destined for the dorsal limb expressing semaphorin3F are repelled by cRET in
the ventral limb.
E. More than one of the above are correct.
Nsci 4100 – Midterm Exam 2
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24. Which of the following is an important element of the clutch hypothesis?
A. Cell surface adhesion molecules such as integrin anchor actin filaments and prevent
retrograde flow.
B. Depolymerization of microtubules stabilizes the filopodia.
C. Myosin retracts actin filaments from the filopodia.
D. Neurofilaments function as clutches to stop the retrograde flow of microtubules.
AC E. More than one of the above are correct.
25. Which of the following is NOT a component of the signal transduction cascade that leads to
growth cone collapse in response to a repellent guidance cue?
A. RhoA

B. Rac
C. myosin II
D. ROCK
E. More than one of the above are not components of this signaling cascade.
26. If you sever a growing axon from its cell body, what activities do you expect can continue (at
least for a while)?
A. The growth cone motility will continue, and the growth cone moves ahead.
B. Protein synthesis in the growth cone can continue.
C. Polymerization of microtubules in the growth cone can continue.
D. Two of the above are correct.

E. All three of the above are correct.
Class 24-25 specificity
27. In each sensory system, the spatial pattern of the position of the receptor cells relative to
one another is maintained in the synapses in each successive step of the pathway. This is
referred to a topographic pattern of connections. In which sensory system, is this type of
organization not present?
A. vision
B. hearing
C. somatosensory

D. olfaction
E. None of the above are correct, since all of these systems have a spatial topography
in their connections.
28. In humans, which set of retinal ganglion cell axons do NOT cross the midline in the optic
chiasm?
A. axons from dorsal side of both retinas

B. axons from the temporal side of both retinas
C. axons from the nasal side of both retinas
D. axons from dorsal side of the right retina and the temporal side of the left retina
E. axons from the ventral side of both retinas
29. As the growth cones of growing retinal axons enter the tectum, they immediately …
A. form synapses.
B. speed their growth.

C. defasciculate.
D. spread forming larger, broader growth cones.
E. More than one of the above are correct.
Nsci 4100 – Midterm Exam 2
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30. A number of mechanisms have been proposed to explain how retinal axons make a
topographic pattern of connections in the central visual nuclei. Which of the following
mechanism seems least likely to be relevant in this system?

A. timing of axon growth into the target
B. topographic order among the growing retinal axons
C. selective retention based on activity dependent mechanisms
D. chemospecificity
31. Which of the following receptor-ligand pairs has NOT been implicated in development of the
topographic pattern of retinotectal connections?
A. EphA - ephrinA
B. EphB - ephrinB

C. Frizzled - Slit
D. Ryk - Wnt
E. More than one of the above are correct.
32. Which of the following is a characteristic of ephrinBs?
A. A GPI-linked cell surface protein

B. Capable of functioning as a ligand or a receptor
C. Can function as a transcription factor
D. Can function as a Wnt receptor
E. More than one of the above are correct.
33. Which of the following statements regarding olfactory receptor proteins is NOT true?
A. Humans typically express 339 different olfactory receptor proteins.
B. Olfactory receptor neurons in the nasal epithelium express an olfactory receptor
protein on their axons that grow into the brain.
C. Olfactory receptor neurons in the nasal epithelium express an olfactory receptor
protein on their dendrites.

D. Neurons in the olfactory bulb express an olfactory receptor protein on their axons
that grow into the nasal epithelium.
E. All of the above are true, and none are false.
34. Cell adhesion molecules like N-CAM or L1 can have varying amount of polysialic acid
(PSA). What effect does an increased amount of PSA on CAMs in the environment of
growing axons likely to have on those axons?

A. Axon substrate adhesion will be reduced.
B. Axon substrate adhesion will be increased.
C. Axons will be repelled.
D. Axons will detect a tropic factor and be attracted to its source.
Class 26 synapse formation
35. Compared to the action potentials of mature neurons, the first action potentials of
developing neurons are of …
A. shorter duration.

B. longer duration.
C. greater amplitude (i.e. more positive voltage).
D. lesser amplitude.
Nsci 4100 – Midterm Exam 2
page 7
36. Neuroligins are described as anchoring the synapse because they …
A. bind neurexins in the presynaptic membrane.
B. bind neurexins in the postsynaptic membrane.
C. bind neurotransmitter receptor proteins via scaffolding proteins.
D. bind to extracellular matrix molecules in the synaptic cleft.
AC E. More than one of the above are correct.
37. During synaptogenesis, an influx of Ca++ into the growth cone triggers …
A. formation of an adherens junction.

B. fusion of coated vesicles at the site in which a synapse will form.
C. aggregation of neurotransmitter receptors.
D. accumulation of synaptic vesicles.
38. Which of the following proteins binds directly to acetylcholine receptors (AchR) in muscle
fibers?
A. agrin
B. dystroglycan
C. synaptic laminin (s-laminin)

D. rapsyn
E. More than one of the above are correct.
Class 27 research from Chen
[Everyone received credit for the following question.]
39. Which of the following result most strongly points to LAD-2 as mediating the repulsive action
of semaphorin signaling?
A. LAD-2 and semaphorin mutants show axon guidance defects.
B. Axon guidance defects induced by ectopic semaphorin expression is enhanced in
LAD-2 mutants.

C. Axon guidance defects induced by ectopic semaphorin expression is not enhanced
in LAD-2 mutants.
D. LAD-2 and semaphorin biochemically interact.
Class 28 paper discussion
40. Retinal ganglion cells in the developing mouse retina that express Zic2 are likely to …
A. send their axons to the ipsilateral side of the brain
B. synapse with neurons in the posterior region of the superior colliculus
C. express EphB1
D. express Wnt3
A/C E. More than one of the above are correct.
The End!
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