Unit12 - Unit 12 1 UNIT 12 PART A: OXIDATIVE...

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Unit 12 1 U NIT 12 P ART A: O XIDATIVE P HOSPHORYLATION P ART B: T HE L IGHT R EACTIONS OF P HOTOSYNTHESIS P ART A: O XIDATIVE P HOSPHORYLATION Glycolysis and the citric acid cycle catalyze the oxidation of carbohydrates and fats to CO 2 , but the resulting electrons are left on the coenzymes NADH and FADH 2 . Oxidative phosphorylation is the process by which the energy of these electrons is used to make ATP. The electrons pass down a series of redox coenzymes and prosthetic groups or "carriers", called the "respiratory chain", to the final acceptor, oxygen. The process by which this passage of electrons is coupled to ATP synthesis has been shown to involve the transport of protons across the mitochondrial inner membrane to form an electrochemical proton gradient which is the "high energy intermediate" of the energy coupling. Elucidation of this "chemiosmotic" coupling was a particularly dramatic chapter in the history of biochemistry because it involved such radically new concepts. Your first goal should be to understand the basic principles of electron transfer, proton gradients, and ATP synthesis before you tackle the details of each redox carrier, the stoichiometries of proton transport reactions, and the mechanism of ATP synthesis Assignment: Nelson & Cox, pp. 690 – 722.
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Unit 12 2 1. The mitochondrion is the eukaryotic organelle where the TCA cycle and oxidative phosphorylation take place. a. Study the diagram and description of a mitochondrion in Fig. 19-1 (p. 691), making special note of the presence of cristae, differences between the inner and outer membranes, the matrix, and the intermembrane space (not labeled on the diagram). Note that mitochondria are found in almost all eucaryotic cells (animal and plant), but not in procaryotic cells. b. Indicate the locations of the electron carriers of the respiratory chain and the reactions of the TCA cycle on the diagram of the mitochondrion (Fig. 19-1, p. 691). 2. The prosthetic groups carry electrons (hemes, Cu ++ , and FeS) or hydrogen atoms (Q, FMN, FAD, NAD). The ones that carry only electrons are called electron carriers. Those that carry protons as well as electrons are called hydrogen carriers. Look at their structures on Figs. 19-2 (p. 693), 19-3 (p. 694), and 19-5 (p. 695) and note where the electrons and protons go.
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Unit12 - Unit 12 1 UNIT 12 PART A: OXIDATIVE...

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