exam_1_review_questions

exam_1_review_questions - Exam 1: BIS 104 Summer Session II...

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Exam 1: BIS 104 Summer Session II 2009 Practice Problems Chapter 17: The Cell Cycle Concept Review Questions: 1) Discuss how CDK activity is modulated by the following proteins: (a) cyclin, (b) p21, (c) p15. 2) What stimulus is required for quiescent cells to reenter the cell cycle? What events occur after stimulation? 3) After addition of serum to G 0 -arrested mammalian cells, two classes of genes are expressed: early-response genes and delayed-response genes. Explain why expression of delayed-response genes is blocked by inhibitors of protein synthesis but expression of early-response genes is not. Data Analysis Question: (This question should be challenging for you.) 4 ) As genes encoding cyclin-dependent kinases were cloned from fission yeast ( S. pombe ), budding yeast ( S. cerevisiae ), and animal cells, investigators working in plant systems designed experiments to determine whether plants also possessed CDKs that functioned as the catalysts for cell cycle progression. To isolate a cDNA (review what a cDNA is and how it is created by reading pages 544-546 in your textbook) encoding a CDK in maize (corn), investigators aligned the predicted amino acid sequences of human cdc2 , S. pombe cdc2 , and S. cerevisiae cdc28 (same gene as cdc2 in humans) genes (see the figure below). Degenerate oligonucleotide PCR primers corresponding to the boxed amino acids were generated and a DNA fragment of the expected size was synthesized by PCR using these primers and maize cDNA library (review cDNA library on pages 540-543 in your text) as a template. Why were the boxed regions selected as the basis for primer design?
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The PCR product was then used as a probe to screen the maize cDNA library, and a full- length cDNA clone was isolated. The clone was sequenced, and the predicted amino acid sequence was found to be 64% identical to human cdc2 and 63% identical to S. pombe cdc2 and to S. cerevisiae cdc28 . What does the level of sequence similarity suggest about the evolution of cdc2 genes? A complementation experiment (complementation review pages 556-558 in your text) was performed with S. cerevisiae cells possessing a temperature-sensitive cdc28 mutation (temperature sensitive mutations review pages 556-558 of your text). Wild-type cells, cdc28 ts cells, and cdc28 ts cells transfected with the maize cdc2 cDNA under the influence of a strong promoter were grown at the permissive (25 ° C) or restrictive (37 ° C) temperatures. Cell proliferation was monitored by the growth of colonies on the culture plates (shown in the figure below).
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Why do the cdc28 ts cells form colonies at 25 ° C but not 37 ° C? What is the significance of colony formation of the cdc28 ts + maize cdc2 cells at 37 ° C? What does this experiment tell us about the functional homology of cyclin-dependent kinase genes among eukaryotic
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This note was uploaded on 03/20/2010 for the course BIS BIS 104 taught by Professor Privalsky during the Spring '09 term at UC Davis.

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exam_1_review_questions - Exam 1: BIS 104 Summer Session II...

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