Smith - Example Questions Flashcards
An oncogene is a gene which
A. Generally shows a recessive phenotype when mutated
B. Will cause cells to proliferate when it is mutated
C. Regulated normal cell growth and division
D. Is an anti proliferative gene
E. Is activated during mitosis
B. will cause cells to proliferate when it is mutated
One way in which p53 can arrest the cell cycle is to A. Phosphorylate Rb B. Activate Bcl-2 C. Induce CDKI D. Phosphorylate Ras E. Activate cyclin D
C. Induce CDKI
CDKI are involved in the arrest of the cell cycle during G1
One key difference between that PDGF and the cytokine-induced signal transduction pathways is that
A. PDGF binds a membrane bound receptor, cytokines bind to cytoplasmic receptors
B. PDGF activates RAS, cytokine pathways inactivate RAS
C. The PDGF receptor oligomerizes, the cytokine receptors don’t
D. PDGF path involves kinases, cytokine pathway does not
E. The PDGF pathway ultimately activates TFs in the nucleus, the cytokine pathway activates TFs in the cytoplasm
E. The PDGF pathway ultimately activates TFs in the nucleus, the cytokine pathway activates TFs in the cytoplasm
Which of the following Ras mutations would be most likely to lead to tumor formation?
A. A mutation that renders it insensitive to the activity of GAP
B. A mutation that leads to its over expression
C. A mutation that renders it insensitive to the activity of Sos
D. A mutation that renders it incapable of activating MAPK path
E. None of the above RAS is a TS and any mutations would likely be recessive
A. A mutation that renders it insensitive to the activity of GAP
GAP inactivates Ras by stimulating its intrinsic GTP activity, if you have Ras that is insensitive to GAP then it will always be active
Which of the following statements about hereditary forms of retinoblastoma is most likely to be true?
A. Patients were born with a deletion in both copies of the Rb gene
B. Patients were born with both copies of the Rb gene intact.
C. Patients were born with a deletion or loss of function in one copy of the Rb gene.
D. Patients were born with a mutation in the p53 gene.
E. None of the above; the disease retinoblastoma and the Rb gene were eventually shown to be unrelated
C. Patients were born with a deletion or loss of function in one copy of the Rb gene.
For the genes in the following list, label the oncogenes with O, TFs with TF and tumor suppressor genes with TS Ras: STAT: Rb: p53: Src:
Ras: O STAT: TF Rb: TS p53: TS Src: O
Which of the following outcomes would be most likely upon overexpression of an active caspase? A. Cell proliferation B. Cell differentiation C. Tumor formation D. Apoptosis E. Inactivation of BCL-2
D. Apoptosis
because when you inactivate caspases you are allowing the cell to survive, activating caspases induces apoptosis therefore an overexpression of active caspases would cause intense apoptosis
Some tumors may be caused by viruses. Which of the following is an oncogenic mechanism associated with Rous sarcoma virus?
A. The viral genome inserts into the host such that host oncogenes will now be under the control of strong viral promoters that enhance their expression
B. A DNA copy of the viral RNA can cause abnormal activation of proto-oncogenes
C. The virus induces a single point mutation in a host tumor suppressor gene.
D. A viral oncogene is introduced that is mutated homolog of a normal cellular gene
E. None of the above; viruses causing cancer is just crazy talk.
D. A viral oncogene is introduced that is mutated homolog of a normal cellular gene
In breast cancer, expression of the several cyclins is increased as a result of gene amplification or chromosomal translocation. What is the most likely explanation for why this would lead to cancer?
A. This would lead to RB activation
B. This would lead to hyperphosphorylation of Rb, leading to cell proliferation
C. This would lead to induction of CDK-1
D. This would lead to apoptosis
B. This would lead to hyperphosphorylation of Rb, leading to cell proliferation
Which of the following elements is mutated to a constitutively active form in 30 percent of all cancers? A. Ras B. Rb C. P53 D. STAT E. PDGF
A. Ras
Which of the following is NOT a common signaling molecule that tells cells when to grow and divide?A. Protein tyrosine kinase B. Insulin C. PDGF D. IL-1 E. Cytokine
A. Protein tyrosine kinase
PTK is responsible for transferring a phosphate from ATP to a protein
Which of the following is a common receptor molecule that growth factors bind to? A. Protein tyrosine kinase B. Insulin C. PDGF D. IL-1 E. Cytokine
A. Protein tyrosine kinase
When a growth factor binds to its receptor molecule, a common sequence of events is:
A. Creation of docking sites-oligomerization of the receptor-activation of the receptor-recruitment and activation of signling enzymes
B. Oligomerization of the receptor-creation of docking sites-recruitment and activation of signaling enzymes-activation of the receptor
C. Activation of receptor-oligomerization of receptor-creation of docking sites-recruitment and activation of signaling enzymes
D. Oligomerization of the receptor, activation of the receptor, creation of docking sites, recruitment and activation of signaling enzymes
D. Oligomerization of the receptor, activation of the receptor, creation of docking sites, recruitment and activation of signaling enzymes
14) Which of the following is most likely to activate cell proliferation via the mitogen-activated protein kinase (MAPK) pathway? A. p53 B. PDGF C. Interleukin-10 D. STAT E. JAK
B. PDGF
The molecular switch of PDGF is Ras which is the ultimate activator of MAPK
A mutation in Ras that causes it to be constitutively active would likely lead to
A. Apoptosis
B. Tumor formation
C. p53 activation
D. Caspase & activation
E. An immediate increase in intracellular calcium
B. Tumor formation
