Review Questions
What is the function of a phosphatase?
- A phosphatase removes phosphorylated amino acids from proteins.
- A phosphatase removes the phosphate group from phosphorylated amino acid residues in a protein.
- A phosphatase phosphorylates serine, threonine, and tyrosine residues.
- A phosphatase degrades second messengers in the cell.
Hint:
B
How does NF-κB induce gene expression?
- A small, hydrophobic ligand binds to NF-κB, activating it.
- Phosphorylation of the inhibitor Iκ-B dissociates the complex between it and NF-κB, and allows NF-κB to enter the nucleus and stimulate transcription.
- NF-κB is phosphorylated and is then free to enter the nucleus and bind DNA.
- NF-κB is a kinase that phosphorylates a transcription factor that binds DNA and promotes protein production.
Hint:
B
Apoptosis can occur in a cell when the cell is ________________.
- damaged
- no longer needed
- infected by a virus
- all of the above
Hint:
D
What is the effect of an inhibitor binding an enzyme?
- The enzyme is degraded.
- The enzyme is activated.
- The enzyme is inactivated.
- The complex is transported out of the cell.
Hint:
C
How does PKC’s signaling role change in response to growth factor signaling versus an immune response?
- PKC interacts directly with signaling molecules in both cascades, but only exhibits kinase activity during growth factor signaling.
- PKC interacts directly with signaling molecules in growth factor cascades, but interacts with signaling inhibitors during immune signaling.
- PKC amplifies growth factor cascades, but turns off immune cascades.
- PKC is activated during growth factor cascades, but is inactivated during immune response cascades.
Hint:
B
A scientist notices that a cancer cell line fails to die when he adds an inducer of apoptosis to his culture of cells. Which hypothesis could explain why the cells fail to die?
- The cells have a mutation that prevents the initiation of apoptosis signaling.
- The cells have lost expression of the receptor for the apoptosis-inducing ligand.
- The cells overexpress a growth factor pathway that inhibits apoptosis.
- All of the above.
Hint:
D