Chapter 9 - Chapter 9 Cellular Respiration Harvesting...

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Unformatted text preview: Chapter 9 Cellular Respiration: Harvesting Chemical Energy Giant panda Obtains energy for its cells by eating plants Figure 9.1 Energy Flows into ecosystem as sunlight & leaves as heat Light energy ECOSYSTEM CO 2 + H 2 O Photosynthesis in chloroplasts Cellular respiration in mitochondria Organic molecules + O 2 ATP powers most cellular work Heat energ y Figure 9.2 Concept 9.1: Catabolic pathways yield energy by oxidizing organic fuels Breakdown of organic molecules is exergonic To keep working Cells must regenerate ATP Redox Reactions: Oxidation and Reduction Catabolic pathways yield energy Due to transfer of electrons Oxidation (LEO) Substance loses electrons, or is oxidized Reducing agent Reduction (GER) Substance gains electrons, or is reduced Oxidizing agent Examples of redox reactions Na + Cl Na + + Cl – becomes oxidized (loses electron) becomes reduced (gains electron) Oxidation of Organic Fuel Molecules During Cellular Respiration cellular respiration Glucose is oxidized and oxygen is reduced Cellular respiration Oxidizes glucose in a series of steps (gasoline explosion drives car not efficient) C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + Energy becomes oxidized becomes reduced Electrons from organic compounds Usually first transferred to NAD + , a coenzyme NAD + H O O O O – O O O – O O O P P CH 2 CH 2 HO OH H H HO OH HO H H N + C NH 2 H N H NH 2 N N Nicotinamide (oxidized form) NH 2 + 2[H] (from food) Dehydrogenase Reduction of NAD + Oxidation of NADH 2 e – + 2 H + 2 e – + H + NADH O H H N C + Nicotinamide (reduced form) N Figure 9.4 NADH - reduced form of NAD + Passes electrons to electron transport chain (E.T.C.) E.T.C. Passes electrons in series of steps instead of one explosive reaction Uses energy from electron transfer to form ATP If electron transfer is not stepwise Large release of energy occurs As in reaction of hydrogen and oxygen to form water Free energy, G H 2 O Explosive release of heat and light energy Figure 9.5 A H 2 + 1 / 2 O 2 2 H 1 / 2 O 2 (from food via NADH) 2 H + + 2 e – 2 H + 2 e – H 2 O 1 / 2 O 2 Controlled release of...
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This note was uploaded on 01/18/2011 for the course BIO 103 taught by Professor Sanders during the Spring '10 term at Northwestern IA.

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Chapter 9 - Chapter 9 Cellular Respiration Harvesting...

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