Cell Division slide show 2008 revised

Cell Division slide show 2008 revised - Cell Division...

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Cell Division Regulation and Checkpoints
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In vitro mitosis. What is in the frog egg cytoplasm?
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Daughter cells Daughter cell
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Cyclin-Cdk Complexes The cell cycle is regulated by cyclical changes in the activity of Cdks [kinases]. These kinases themselves are regulated by a complex array of enzymes and regulatory proteins. There are several types of Cdks. The major regulatory proteins are cyclins. Cdks themselves have no kinase activity unless they are bound to a cyclin. Cyclins were named because they undergo a cycle of synthesis and degradation in each cell cycle. There are four classes of cyclins, each defined by the stage of the cell cycle at which they bind Cdks and function. Cyclical changes in cyclin protein levels result in the assembly and activation of cyclin-cdk complexes; this activation in turn triggers cell cycle events. The classes are: G 1 -Cdk, G 1 /S Cdk, S-Cdk, M-Cdk G 1 -Cdk regulates START. G 1 /S-cyclins which activate Cdks late in G 1 and so trigger progression through the START phase, or commitment phase to enter the cell cycle. S-cyclins. These bind Cdks soon after progression through START and aid chromosome duplication. . S-cyclins remain elevated until mitosis, and these cyclins also control some early mitotic events. M-cyclins activate Cdks that stimulate entry into mitosis at the G2/M checkpoint. They are destroyed in mid-mitosis. Cyclins are often designated by letters: A, B, D. E. Cdks are often called Cdcs Regulatory proteins are grouped by their activities: Kinases ,Phosphatases , Inhibitors, Ubiquitin ligases and associated proteins.
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Cyclin and cyclin-dependent kinase [Cdk]
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Regulation of Cyclin-Cdk complex by activating and inactivating kinases or by inhibition by a cdk inhibitor protein [CKI] Structural basis of Cdk activation: Cyclin binding causes a conformational change partially activating the enzyme. A Cdk-activating kinase [CAK] phosphorylates a particular amino acid fully activating the cdk kinase.
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Cell Division slide show 2008 revised - Cell Division...

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