BIS104 Edwards SSI06 FINAL - Page 4

BIS104 Edwards - phase where the cell cycle can be interrupted if the surveillance system detects abnormalities in the DNA or in chromosome

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PART II 3. How is the protein ubiquitin involved in the regulation of the cell cycle? (4 pts) The availability of cyclin proteins is required for th activation of the cdk cell cycle engine. The half-life of cyclin proteins is regulated by the attachment of ubiquitin molecules that mark them for degradation. Therefore, one level of cell cycle control depends on the balance of synthesis and degradation of cyclins. 4. What is the relationship between ubiquitins and proteasomes? (4 pts) Proteins that become ubiquitinated are shuttled to the cytoplasm where they are degraded by the proteolytic compartment of the proteasome. 5. Define the term “cell cycle check-point” and describe why check points are important for normal cell function (4 pts) Check points are found at intervals in the cell cycle between G1 and S-phase and between G2 and M-
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Unformatted text preview: phase where the cell cycle can be interrupted if the surveillance system detects abnormalities in the DNA or in chromosome alignment. This prevents progress of defective cells and an opportunity for repair. 6. How does the subcellular localization of specific regulatory proteins contribute to the regulation of the cell cycle? (4 pts) The distribution of cyclins, based on their phosphorylation state, between cytoplasm and nucleus determines their availability to complex with cdKs. Shuttling of active vs inactive p53 from nucleus to cytoplasm by MDM2 determines p53 availability to be activated by the ATM / chck2 sensors. Page 4 Name ______________________________ Demo...
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This note was uploaded on 05/31/2010 for the course BIO 1B taught by Professor Carlson,mischel,power during the Spring '07 term at University of California, Berkeley.

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