Bio151 Sp13 Exam 3 answer key

3 pts what information about brainless would be

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Unformatted text preview: as the cell's energy source. When lactose is present, the operon is turned on to metabolize the lactose. However, when lactose is not present, the operon is turned down to help the cell conserve energy. The preferred energy source of the cell is glucose, though, so when glucose is present, the cell will use glucose instead of any other energy source (including lactose). In order to not waste energy synthesizing the lac operon products when glucose is present in addition to lactose, the cell needs an additional control system to prevent lac operon expression in the presence of glucose. Question 2 (7 pts) A) (3 pts) When an enzyme is treated with a competitive inhibitor, why does Km change and Vmax remain constant? Competitive inhibitor binds in the active site of the enzyme and competes with substrate for binding to the enzyme’s active site. This changes the apparent Km of the enzyme for the substrate – not because it’s changing the actual binding affinity, but because competitive inhibitor makes is look like the enzyme is having a hard time finding the substrate. But, Vmax can be reached, eventually, because you can keep adding substrate and eventually out- compete inhibitor for the enzyme’s active site. 4 Bio151 Sp13 Name: Exam 3 Prof. Francis Discussion Section number or TA’s name or DS day/time: B) (4 pts) Draw a graph to represent how this might look (so two lines representing with and without inhibitor). Question 3 (6 pts) Reporter genes...
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This note was uploaded on 01/21/2014 for the course BIO 151 taught by Professor Randallphillis during the Fall '12 term at UMass (Amherst).

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