Question 1

Mosaic analysis studies have demonstrated that:

Accepted Answer

A)  The product of the Boss gene is required in the future R7 cell to determine R7 cell fate. 
B)  The product of the Sevenless gene is required in the future R7 cell to determine R7 cell fate. 
C)  the product of the Sevenless gene is required in the R8 cell to determine R7 cell fate. 
D)  the product of the Sevenless gene acts cell nonautonomously to determine R7 cell fate. 
E)  All of the above 
A)  The product of the Boss gene is required in the future R7 cell to determine R7 cell fate. 
B)  The product of the Sevenless gene is required in the future R7 cell to determine R7 cell fate. 
C)  the product of the Sevenless gene is required in the R8 cell to determine R7 cell fate. 
D)  the product of the Sevenless gene acts cell nonautonomously to determine R7 cell fate. 
E)  All of the above

Question 2

What phenotype would be expected of a fruit fly with a mutation in the Ras gene that prevented its product from interacting with GAP1? Briefly explain your reasoning.

Accepted Answer

This mutation would prevent th

Question 3

Surprisingly, nasal axons mistarget along the A-P axis in ephrin-A5 knockout mice. In which cells is ephrin-A5 necessary for normal nasal axon targeting?

Accepted Answer

A)  In the posterior tectum, via forward signaling 
B)  In the anterior tectum, via forward signaling 
C)  In the nasal RGC axons, via reverse signaling 
D)  In the nasal RGC axons, via forward signaling 
E)  In the temporal RGC axons, via reverse signaling 
A)  In the posterior tectum, via forward signaling 
B)  In the anterior tectum, via forward signaling 
C)  In the nasal RGC axons, via reverse signaling 
D)  In the nasal RGC axons, via forward signaling 
E)  In the temporal RGC axons, via reverse signaling

Question 4

Based on neural explant assays, netrin behaves as a:

Accepted Answer

A)  attractive short-range cue. 
B)  repulsive short-range cue. 
C)  attractive long-range cue. 
D)  repulsive long-range cue. 
E)  c and d 
A)  attractive short-range cue. 
B)  repulsive short-range cue. 
C)  attractive long-range cue. 
D)  repulsive long-range cue. 
E)  c and d

Question 5

When Sperry and colleagues ablated the posterior (temporal) RGCs, the remaining anterior (nasal) RGCs projected to the posterior tectum. Is this definitive evidence that these neurons are programmed early in development to project only to that part of the brain? Briefly explain your reasoning.

Accepted Answer

It is important to remember that this re

Question 6

Which experiment first demonstrated the sufficiency of competing ocular inputs to produce spatial segregation in the brain?

Accepted Answer

Transplantation of an eye primordium in

Question 7

Expressing EphA3 in Islet2+ RGCs:

Accepted Answer

A)  provided additional support for the competition model. 
B)  demonstrated that temporal axon A-P targeting depends on absolute and not relative levels of EphA3. 
C)  demonstrated that temporal axon A-P targeting depends on relative and not absolute levels of EphA3. 
D)  a and b 
E)  a and c 
A)  provided additional support for the competition model. 
B)  demonstrated that temporal axon A-P targeting depends on absolute and not relative levels of EphA3. 
C)  demonstrated that temporal axon A-P targeting depends on relative and not absolute levels of EphA3. 
D)  a and b 
E)  a and c

Question 8

What are the two major types of mechanisms used for wiring the nervous system? Give a specific example of each one.?

Accepted Answer

The first mechanism was proposed by Sper

Question 9

Which of the following general principles can be gleaned from developmental studies of the visual system in vertebrates?

Accepted Answer

A)  Connection specificity that distinguishes discrete cell types is more likely to be determined by molecular cues. 
B)  Connection specificity that chooses between similar cells tends to involve neuronal activity and competition. 
C)  Initial targeting by neuronal processes tends to be activity-independent. 
D)  Refinement of neuronal processes tends to be activity-dependent. 
E)  All of the above 
A)  Connection specificity that distinguishes discrete cell types is more likely to be determined by molecular cues. 
B)  Connection specificity that chooses between similar cells tends to involve neuronal activity and competition. 
C)  Initial targeting by neuronal processes tends to be activity-independent. 
D)  Refinement of neuronal processes tends to be activity-dependent. 
E)  All of the above

Question 10

Place the following events in chronological order.
A. Expression of Spineless in R7 cells
B. Expression of Boss in R8 cells
C. Expression of rhodopsins in R8 cells
D. Induction of R7 cell fate
E. Induction of R8 cell fate

Accepted Answer

E, B, D, A, C. The R8 cell must acquire

Question 11

Genetic loss- and gain-of-function mosaic analysis was used to elucidate the roles of several proteins in medulla layer-specific targeting.
A. What outcome(s) would one expect in R7 vs. R8 cells from the experimental misexpression of Frazzled specifically in R7 cells?
B. What outcome(s) would one expect in R7 vs. R8 cells from a mosaic experiment in which Senseless was removed from a presumptive R7 cell?

Accepted Answer

Misexpressing Frazzled in the R7 cells w

Question 12

The signal from R7 that induces Rh5 expression in R8 is as yet unknown. What ommatidial phenotypes would be expected of a loss-of-function mutant for the gene encoding this signal?

Accepted Answer

A)  All R7 cells would express Rh3. 
B)  All R7 cells would express Rh4. 
C)  All R8 cells would express Rh5. 
D)  All R8 cells would express Rh6. 
E)  Both b and d 
A)  All R7 cells would express Rh3. 
B)  All R7 cells would express Rh4. 
C)  All R8 cells would express Rh5. 
D)  All R8 cells would express Rh6. 
E)  Both b and d

Mosaic analysis studies have demonstrated that:

What phenotype would be expected of a fruit fly with a mutation in the Ras gene that prevented its product from interacting with GAP1? Briefly explain your reasoning.

Surprisingly, nasal axons mistarget along the A-P axis in ephrin-A5 knockout mice. In which cells is ephrin-A5 necessary for normal nasal axon targeting?

Based on neural explant assays, netrin behaves as a:

When Sperry and colleagues ablated the posterior (temporal) RGCs, the remaining anterior (nasal) RGCs projected to the posterior tectum. Is this definitive evidence that these neurons are programmed early in development to project only to that part of the brain? Briefly explain your reasoning.

Which experiment first demonstrated the sufficiency of competing ocular inputs to produce spatial segregation in the brain?

Expressing EphA3 in Islet2⁺ RGCs:

What are the two major types of mechanisms used for wiring the nervous system? Give a specific example of each one.?

Which of the following general principles can be gleaned from developmental studies of the visual system in vertebrates?

Place the following events in chronological order. A. Expression of Spineless in R7 cells B. Expression of Boss in R8 cells C. Expression of rhodopsins in R8 cells D. Induction of R7 cell fate E. Induction of R8 cell fate

The signal from R7 that induces Rh5 expression in R8 is as yet unknown. What ommatidial phenotypes would be expected of a loss-of-function mutant for the gene encoding this signal?

An Invitation to Neurobiology

Signaling Within Neurons

Signaling Across Synapses

Vision

Olfaction, Taste, Audition, and Somatosensation

Wiring of the Nervous System

Motor and Regulatory Systems

Sexual Behavior

Memory, Learning, and Synaptic Plasticity

Brain Disorders

Evolution of the Nervous System

Ways of Exploring

Filters

Exam 5: Wiring of the Visual System

Mosaic analysis studies have demonstrated that:

What phenotype would be expected of a fruit fly with a mutation in the Ras gene that prevented its product from interacting with GAP1? Briefly explain your reasoning.

Surprisingly, nasal axons mistarget along the A-P axis in ephrin-A5 knockout mice. In which cells is ephrin-A5 necessary for normal nasal axon targeting?

Based on neural explant assays, netrin behaves as a:

When Sperry and colleagues ablated the posterior (temporal) RGCs, the remaining anterior (nasal) RGCs projected to the posterior tectum. Is this definitive evidence that these neurons are programmed early in development to project only to that part of the brain? Briefly explain your reasoning.

Which experiment first demonstrated the sufficiency of competing ocular inputs to produce spatial segregation in the brain?

Expressing EphA3 in Islet2+ RGCs:

What are the two major types of mechanisms used for wiring the nervous system? Give a specific example of each one.?

Which of the following general principles can be gleaned from developmental studies of the visual system in vertebrates?

Place the following events in chronological order. A. Expression of Spineless in R7 cells B. Expression of Boss in R8 cells C. Expression of rhodopsins in R8 cells D. Induction of R7 cell fate E. Induction of R8 cell fate

The signal from R7 that induces Rh5 expression in R8 is as yet unknown. What ommatidial phenotypes would be expected of a loss-of-function mutant for the gene encoding this signal?

An Invitation to Neurobiology

Signaling Within Neurons

Signaling Across Synapses

Vision

Olfaction, Taste, Audition, and Somatosensation

Wiring of the Nervous System

Motor and Regulatory Systems

Sexual Behavior

Memory, Learning, and Synaptic Plasticity

Brain Disorders

Evolution of the Nervous System

Ways of Exploring

Filters

Expressing EphA3 in Islet2⁺ RGCs: