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8 Cards in this Set
- Front
- Back
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The number of cell in an adult tissue or animal is determined by regualated cell proliferation. What else helps determine cell numbers?
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Mitogens: stimulate cell division, primarily by overcoming the intracellular braking mechanism that tend to block progression through the cell cycle
Growth Factors: Stimulate cell growth (an increase in cell mass) by promoting the synthesis and inhibiting the degradation of proteins and other macromolecules Survival Factors: Promote cell survival by surpressing apoptosis |
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In proliferating cells:
a.Rb protein is active b. nutrients are limiting c. growth factors secreted by other cell are bound to receptors d.cyclin-Cdk complexes are inactive e. all Cdk are continuously active |
a. and c.
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What is the cause of the massive amount of programmed cell death of nerve cells (neurons)that occurs in the developing vertebrate nervous system, and what purpose does it serve?
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Programmed cell death, so that cells fit into the normal size and amount that they need to.
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Apoptosis differs from necrosis in that:
a. necrosis happens more frequently b. necrosis causes DNA to fragment c. in necrosis uses a kinase cascade and apoptosis uses a protease cascade d. necrosis contributes to kinase cascade and apoptosis uses a protease cascade e. necrosis contributes to cancer when dergulated f. necrosis occurs only in injured or abnormal cells |
c.
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activated intracellular proteases directly mediate programmed cell death by:
a. cleaving other proteases b. digesting the nuclear DNA c.activating phagocytosis by a neighboring cell d. destroying survival signals e. elicting killer signals form other cells f. cleaving various key proteins in the cell |
f.
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The protein p53 is activated when DNA is damaged and helps arrest the cell cycle in G1, allowing time for the cell to repair is DNA before replicating it. Activated p53 arrests the cell cycle by stimulating the transcription of the gene that encodes the Cdk inhibitor protein p21. Mutations that inactivate p53 contribute to 50% of human cancers. Would you classify p53 as a tumor-suppressor gene or a proto-oncogne? Explain your answer.
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You answer yourself
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stem cells:
a. cycle btw an undifferentiated and a differentiated state b. are required to renew all cell types c. look like the specialized cells of the tissue d. migrate to where they are needed e. can sometimes progeny of more than one cell type |
d.
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match the function of the cell-cell junction with the correct name.
a. seals neighboring cell together in an epithelial sheet to prevent leakage of molecules btw them_____1___________ c. anchors the intermediate filaments in a cell to the basal lamina_______2________ b. joins intermediate filaments in one cell to those in a neighbor_________3_______ d. joins an actin bundle in one cell to a similar bundle in a neighboring cell__________4__________ e. allows the passage of small water-soluble ions and molecules in the cytosol________5_______ |
1.tight junctions
2.hemidesmosome 3.desmosome 4.adherens junction 5.gap junction |
