EMQ 10. Theme: Contact inhibition
From the options below, identify the element described in each of the items in the list.
A BAX
B Cancer cells
C Cyclin dependent kinase inhibitors (CKIs)
D Cytochrome c
E Neurons
F Oocytes
G p53
H Retinoblastoma protein (Rb)
I Securin
J Skeletal muscle cells
K Wee1
1. Reduced or absent contact inhibition is characteristic of this type of cell.
Your Answer:
Your Answer:
Answer: B, Cancer cells. In a culture dish, cancer cells are seen to pile up because they keep dividing even
when the cells have covered the surface of the dish. In the body, cancer cells keep dividing, forming a tumor that pushes other tissues aside. See book page 306.
2. This class of proteins includes p16INK4a and p27KIP1. They are synthesized when cells contact other cells,
and act to inhibit protein kinases necessary for cell cycle progression.
Your Answer:
Your Answer:
Answer: C, cyclin dependent kinase inhibitors (CKIs). See book page 306.
3. CDK4 and CDK6, the target of the inhibitor proteins described in the line above, promote DNA synthesis by phosphorylating this protein.
Your Answer:
Your Answer:
Answer: H, retinoblastoma protein. Phosphorylated retinoblastoma releases the transcription factor E2F,
which then activates production of proteins required for DNA synthesis. See book page 305.
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