BIOL201 Lecture Notes - Lecture 18: S Phase, Anaphase-Promoting Complex, Telophase
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Cell size: important to reach the appropriate size. * when conditions are met, also need high concentration of mitotic cyclin. Only when the cyclin activity was highest then there was mpf activity which is a main regulator of mitosis. Cyclin concentration increases linearly over time, yet the mpf activity is coming in waves and only occurs at highest concentration of cyclin. This then drives the cell into mitosis out of g2. The mitotic cdk activity is regulated by wee1, a kinase, and by cdc25, a phosphatase. When the wee1 and cdc25 activity levels are adjusted away from normal, the yeast daughter cell size is affected: two inhibitory phosphate groups are attached to the cdk molecule by inactive complex. enzymes- inhibiting kinases. High wee1 and low cdc25- cells get longer. Have kinase and phosphatase (they always go in opposite directions). First suggestion that wee1 and cdc25 may have opposing activities.