Concentration Cyclin D Cyclin Expression Cycle Cyclin E S Phase Cyclin A G₁ Phase Question 1 (19pts). Regulation of the

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Concentration Cyclin D Cyclin Expression Cycle Cyclin E S Phase Cyclin A G Phase Question 1 19pts Regulation Of The 1 (1.18 MiB) Viewed 37 times

Concentration Cyclin D Cyclin Expression Cycle Cyclin E S Phase Cyclin A G₁ Phase Question 1 (19pts). Regulation of the cell cycle is important! Two central players in cell cycle regulation are CDK and Cyclin. These proteins regulate transitions between different stages of the cell cycle: G1/S, S/G2, G2/M, Metaphase-Anapahase. Cyclin B G2 Phase Mitosis G1 S G2 M1 M2 a. Analyze the western blot at right. Which set of bands (top or bottom) represents cyclin? CDK? Identify which specific cyclin is represented (D,E,A,or B) and explain which transition of the cell cycle is regulated by this CDK/cyclin. M1 represents the onset of mitosis and M2 represents the metaphase-anaphase transition. Rubric (4): correct analysis of cyclin (2pts, Cyclin D,E,A, or B and which row on gel, black or grey arrow is cyclin), and CDK (2, which row on the gel, When is it active?). b. The CDK regulated by Cyclin in the previous question actually becomes active closer to the peak of cyclin abundance. Explain why CDK would not be activated sooner (even though cyclin is present) given the actions of Wee-1, CAK, and Cdc25. Rubric (6): Delay in CDK activation is explained using the activities of Wee1, CAK, and Cdc25). c. A gain of function of mutation in Cdc25 causes cells to divide too early and thus be very small. Specifically, explain the effect of gain of function of the Cdc25 protein on CDK activity. Then explain how the change in CDK activity in a cell with GOF Cdc25 would will affect a specific protein target to cause early onset of DNA replication (S phase). Rubric (4): correct interpretation of the effect on CDK-cyclin with LOF Wee1 (2). Correct interpretation of why the cell divides too early using a specific downstream target (2).