BIOL 200 Chapter Notes - Chapter 7: Prophase, Phragmoplast, Lamin
Document Summary
Recall: in order for the cell to pass into s-phase (and replicate its dna) it must first pass the g1/s checkpoint. G1/s checkpoint controls for is dna damage with transcription regulator called p53. When dna damage is detected, p53 production is upregulated, resulting in the production of cdk inhibitors that will stop the progression of the cell cycle by inhibiting the s-cyclin-cdk complex. Note: p53 is mutated in as many as 50% of all cancers (indication of how important this protein is in the proper function of the cell cycle) Transcription regulator that activates the transcription of another protein p21. Under normal conditions: (no dna damage), p53 is transcribed, translated, and then degraded in the proteasome so that it cannot activate p21 and arrest the cell cycle. When dna damage is detected: a number of protein kinases phosphorylate p53 stops it from getting degraded. Allows it to bind to the regulatory region of the p21 gene and activate its transcription.
