BIOC 212 Lecture Notes - Lecture 27: Pennsylvania Railroad Class P5, Cln3, Apoptosis
22 Mar 2017
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Document Summary
In early embryonic cell cycle cdc20-apc activity rises at end of metaphase: triggers m-cyclin destruction. Since m-cdk activity stimulates cdc20: apc activity, loss of m-cyclin leads to apc inactivation after mitosis allowing m-cyclins to begin accumulating again, b) In cells containing a g1 phase, drop in m-cdk activity in late mitosis leads to activation of hct1-apc (and accumulation of cki proteins) If cell division continued at an unchanged rate where cells starved and stopped growing, daughter cells would become progressively smaller. Yeast cells respond to some forms of nutritional deprivation by slowing rate of progress of cell cycle so that cells have more time to grow. Cell size thus remains unchanged or reduced slightly. Unit of time is cycle time observed when nutrients are in excess. Result is p53 accumulating to high levels and stimulates transcription of gene that encodes cki protein p21. P21 binds and inactivates g1/s-cdk and s-cdk complexes, arresting the cell in g1.
