Midterm 2A key

Midterm 2A key - Mic102/Fa10/Appleman Midterm 2, 17...

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Mic102/Fa10/Appleman Midterm 2, 17 November 2010 This quiz is to represent only your own work . As a UC Davis student, you are bound by an honor code; if you can’t be trusted with that, can you be trusted in a career in, say, the health professions? Not only does this honor code demand personal integrity, but it also requires you to demand integrity from your peers. This quiz is closed book, closed note. Please hand in a blue scantron with the answers to the multiple-choice section of the quiz. Make sure that it has your name, student I.D.#, and Test form A ” filled in. In the last midterm, we were introduced to organisms in the Roseobacter family. These organisms have a variety of metabolic options, summarized in the figure below. They can grow organotrophically on a variety of carbon compounds, and they respire using oxygen, nirate, or manganese as a terminal electron acceptor. They are also capable of phototrophy; they use photosystem II for cyclic photophosphorylation. Roseobacter is sometimes called “the A-An-P-B”, for “Aerobic-Anoxygenic-Photosynthetic Bacteria.” Here’s a cartoon of energy generation in Roseobacter .
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In the following questions, we will be considering the role of Roseobacter in the carbon cycle. 1. Which of these conclusions, based on Roseobacter ’s genome and growth, makes the most sense? a) Roseobacter is an autotroph, since it has chlorophyll— no; there are lots of heterotrophs with chlorophyll, so it’s a non sequitur. b) Roseobacter is a heterotroph, since it does not have a gene for Rubisco— no, there are lots of autotrophs that don’t have a gene for Rubisco, so it’s a non sequitur. c) Roseobacter is an autotroph, since it grows faster when both light and reduced carbon compounds such as acetate are available— no, this could easily describe a photoheterotroph. d) Roseobacter is a heterotroph, since it cannot grow unless it is provided with reduced carbon compounds such as acetate—this is the only statement that makes logical sense. 2. As noted above, Roseobacter grows faster when both light and reduced carbon compounds are available, and it cannot grow without consuming reduced carbon compounds such as acetate. However, when Roseobacter is grown with light and acetate, it also consumes CO 2 , which eventually becomes part of glucose. The E 0 ’ for this reaction is -0.32 V. Which electron donor could Roseobacter use for this reaction? a) NADPH—a quick check of the answer key (the redox table) shows that this can serve as the e- donor for this reaction. b) NADH— no, the reaction would be endergonic c) reduced Ubiquinone (Quinol)— no, the thermodynamics are even worse. d) any one of the above This provides the answer for a couple of the the boxes in the drawing of carbon metabolism. As carbon dioxide is reduced into glucose, NADPH is oxidized to NADP+ . 3.
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This note was uploaded on 04/05/2011 for the course MIC 102 taught by Professor Appleman during the Fall '08 term at UC Davis.

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Midterm 2A key - Mic102/Fa10/Appleman Midterm 2, 17...

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