Question 1

Which of the following molecules is NOT a downstream effector of Ras?

Accepted Answer

A)  Ral-GEFs
B)  PI3K
C)  Grb2
D)  Raf
E)  None of the above C

Question 2

Which of the following domains of Src is its catalytic domain?

Accepted Answer

A)  SH1
B)  SH2
C)  SH3
D)  C-terminus
E)  N- terminus A

Question 3

Which of the following pathways activated downstream of Ras can result in reorganization of the cytoskeleton,playing a role in cell motility?

Accepted Answer

A)  MEK
B)  PI3K
C)  Ral BP1
D)  Erk1
E)  None of the above C

Question 4

Which of the following signaling pathways is in the correct order?

Accepted Answer

A)  Receptor → Sos → Grb2 → Ras
B)  Receptor → Ras → Sos → Grb2
C)  Receptor → Sos → Ras → Grb2
D)  Receptor → Grb2 → Ras → Sos
E)  Receptor → Grb2 → Sos → Ras

Question 5

Following serum starvation,if normal fibroblasts were treated with cycloheximide to shut down cellular protein synthesis,then,when exposed to fresh serum,the cells would

Accepted Answer

A)  Continue to remain viable in a quiescent state.
B)  Express immediate early genes.
C)  Enter a state of senescence.
D)  Die.
E)  None of the above.

Question 6

What happens in cells following stimulation with growth factors?

Accepted Answer

A)  The transcription of all genes required for growth and replication occurs immediately.
B)  There is a delay of several hours before transcription of genes needed for growth occurs.
C)  Some genes required for growth are transcribed immediately,while others are transcribed later,after new transcription factors have been synthesized.
D)  Cell death occurs.
E)  None of the above.

Question 7

Which of the following is NOT true of β-catenin?

Accepted Answer

A)  It binds directly to the Wnt protein.
B)  It associates with Tcf/Lef transcription factors in the nucleus,driving cell proliferation.
C)  It can be degraded when bound to active GSK-3β.
D)  It exists in a soluble pool in the cytosol.
E)  None of the above.

Question 8

Which of the following is NOT true of the son of sevenless Sos)protein?

Accepted Answer

A)  It is a guanine nucleotide exchange factor GEF) .
B)  It is a GTPase-activating protein GAP) .
C)  It is able to activate Ras.
D)  It was initially identified in Drosophila melanogaster.
E)  None of the above.

Question 9

Which of the following does NOT occur downstream of epidermal growth factor binding to its receptor?

Accepted Answer

A)  NF1 is phosphorylated.
B)  NF1 levels are increased.
C)  Ras is GTP-loaded.
D)  The MAPK pathway is activated.
E)  None of the above.

Question 10

In normal cells,Ras-GAPs trigger GTPase activity in order to

Accepted Answer

A)  Maintain Ras in its active state.
B)  Enhance downstream signaling by Ras effectors.
C)  Promote cellular proliferation.
D)  Inactivate Ras signaling.
E)  A and B.

Question 11

Which of the following statements about AKT is FALSE?

Accepted Answer

A)  AKT is activated downstream of PI3K.
B)  AKT activation may inhibit apoptosis through downstream inactivation of Bad.
C)  AKT activation may result in activation of mTOR.
D)  AKT is tethered to the plasma membrane by PIP3.
E)  None of the above.

Question 12

SH2 domains of tyrosine kinases function to

Accepted Answer

A)  Catalyze activation of downstream pathways.
B)  Act as receptors for phosphotyrosine-containing oligopeptide ligands.
C)  Localize the protein to specific sites in the cell.
D)  B and C.
E)  None of the above.

Exam 6: Cytoplasmic Signaling Circuitry Programs Many of the Traits of Cancer