Deserts are not very efficient at converting huge amounts of incident energy from sunlight into plant biomass.  Most ecosystems based on phytoplankton have very low efficiencies, usually less than 0.5%.

Photosynthetic efficiency of an ecosystem as a whole varies between 1% and 2%.

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

The DNA damage checkpoint controlled by p53.

TLS Online TPP Program

#Id: 1489

#Unit 4. Cell Communication and Cell Signaling

p53,  Induces the expression of CDK inhibitor p21 Induces apoptosis

TLS Online TPP Program

#Id: 1490

#Unit 4. Cell Communication and Cell Signaling

p53 transcription is upregulated by growth factor stimulation, as the cell begins preparation for its trip through GI and the important GI to S transition.

TLS Online TPP Program

#Id: 1491

#Unit 4. Cell Communication and Cell Signaling

p53 protein product is regulated by a protein called MDM2, which works through a negative feedback loop.

TLS Online TPP Program

#Id: 1492

#Unit 4. Cell Communication and Cell Signaling

MDM2 transcription is increased by p53. 

TLS Online TPP Program

#Id: 1493

#Unit 4. Cell Communication and Cell Signaling

MDM2 inhibits p53  by targeting it to the ubiquitin-dependent proteosomal degradation pathway.