ps5q_05

Ps5q_05 - MIT Department of Biology 7.014 Introductory Biology Spring 2005 Name Section 7.014 Problem Set 5 Answers to this problem set are to be

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- - MIT Department of Biology 7.014 Introductory Biology, Spring 2005 Name:______________________________________ Section :______ 7.014 Problem Set 5 Answers to this problem set are to be turned in . Problem sets will not be accepted late. Solutions will be posted on the web. Question 1 Organisms can use a variety of carbon and energy sources, depending on their availability in the environment. Oxidation and reduction reactions play critical roles in metabolism, and the relative favorability of these reactions often dictates the type of metabolism an organism will employ in a given situation. For example, organisms that conduct aerobic respiration (like humans) use organic carbon compounds (like glucose) as both their carbon source and their energy source. a) What compound is reduced by the transfer of electrons from glucose? What are the oxidized and reduced forms of this compound? Electrons are then passed down the electron transport chain, sequentially reducing proteins in the chain, in the process creating a proton gradient for ATP synthesis. b) What is the final electron acceptor for organisms performing aerobic respiration? Why do organisms need a final electron acceptor? The reduction of oxygen is a very favorable reaction; in fact oxygen is the most favorable electron acceptor. Organisms conducting respiration in the absence of oxygen do so anaerobically, using other compounds as electron acceptors. c) Consider the following environments where different compounds are present. Circle the compound in each environment most likely to be used as an electron acceptor. Top portion of the table from the Redox handout has been reproduced on page 6 (last page) to help you decide. Environment 1 Environment 2 Environment 3 - NO 3 F e 3+ C H 3 OH NO 2 N O 2 N O 3 - O 2 N O 3 f u m a r a t e Just as electron acceptors are selected in evolution based on thermodynamic favorability, so are electron donors. Whereas respiration uses organic compounds as electron donors, and photosynthesis uses water as an electron donor (to replace the electron excited by light), many organisms use inorganic compounds as electron donors and sources of energy. d) For each electron donor below, give the compound it will be converted to upon oxidation. Circle the compound that will yield the most energy upon oxidation. H
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This note was uploaded on 11/11/2011 for the course BIO 7.012 taught by Professor Lander during the Fall '10 term at MIT.

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Ps5q_05 - MIT Department of Biology 7.014 Introductory Biology Spring 2005 Name Section 7.014 Problem Set 5 Answers to this problem set are to be

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