Vertabrate cells pause in the G1 phaseof the cell cycle until conditions are app
ID: 98487 • Letter: V
Question
Vertabrate cells pause in the G1 phaseof the cell cycle until conditions are appropriate for their entery into Sphase passage through G1 have been difined using mouse 3T3 cells.the serum reguirement can be met by supplying three extracellular growth factors, PDGF,EGF, and IGF1.when these factors are mixed with the appropriente nutrients and added to the nondividing cells,the cells begin S phase 12 hours later. If any one of the factors is left out the cell do not ente S phase.
what do these three factors have in common in terms of their intracellular signaling pathways?
A. What would you observe for S phaseentery timing if cells required all three factors simultaneously?
B.what would you observe if the growth factors acted independently of each other but were not needed simultaneously?
C. If order matters what would you observe for S phase entery?
Explanation / Answer
All three factors are ligands for receptor tyrosine kinase and promote cell survival, proliferation through mTor pathway and angiogenesis.
a. the timing wont be effected but the percent of cells entering S phase would increase.
b. the cells wont enter S phase
c. PDGF turns incubated cells into competent cells on which the IGF / egf act
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