Discussion 8 key Fall 2009

Discussion 8 key Fall 2009 - GENETICS (BIO 325) Discussion...

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GENETICS (BIO 325) FALL 2009 Discussion sheet 8 key _____________________________________________________________________________ _ 1. The genes in the operon are all transcribed together from a single promoter, making a polycistronic mRNA. Therefore, controlling transcription from that promoter controls all the genes simultaneously, a feature found exclusively in prokaryotes. 2. (a) The lac operon would always be turned on, because the repressor cannot turn it off by binding to the operator. (b) Same as (a). (c) The operon would be uninducible. The repressor would remain bound to the operator even in the presence of the inducer. (d) The operon would be transcribed only weakly. Even in the presence of glucose, CAP plus cAMP would be unable to facilitate polymerase binding to the lac promoter. 3. With positive control, an activator protein is needed for transcription to occur, whereas for negative control, a repressor protein prevents transcription from occurring. Both mechanisms commonly act on single genes or operons; the lac operon is an example in which the repressor protein, the product of the
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This note was uploaded on 05/15/2010 for the course BIO 325 taught by Professor Saxena during the Spring '08 term at University of Texas at Austin.

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Discussion 8 key Fall 2009 - GENETICS (BIO 325) Discussion...

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