bio chapter 9 I - Chapter 9: Cellular Respiration Lecture...

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Chapter 9: Cellular Respiration Lecture 14: Bioenergetics I Life is Work -energy flows into an ecosystem as sunlight and leaves as heat -chemical elements recycled -photosynthesis generates oxygen and organic molecules used by the mitochondria of eukaryotes as fuel for respiration -respiration breaks this fuel down generating ATP…waste: CO2 and H20 (materials for photosynthesis) 9.1 C ATABOLIC P ATHWAYS Y IELD E NERGY BY O XIDIZING O RGANIC F UELS Catabolic Pathways and Production of ATP -compounds that can participate in exergonic rxns act as fuels -degrades complex organic molecules rich in potential energy to simper waste products with less energy -some of that energy is taken out of chemical storage and can be used to do works - fermentation : partial degradation of sugars that occurs without the use of oxygen - aerobic respiration : most prevalent and efficient catabolic pathway in which oxygen is consumed as a reactant along with the organic fuel -most eukaryotic and many prokaryotic organisms can carry out aerobic respiration - anaerobic respiration : some prokaryotes use substances other than oxygen as reactants in cimilar process that harvests chemical energy without any oxygen - cellular respiration : aerobic and anaerobic processes -cellular respiration: is often used to refer to the aerobic process -organic compounds + oxygen carbon dioxide + water + energy -although carbs, fats, and proteins can all be processed and consumed as fuel, it is helpful to learn the steps of cellular respiration by tracking the degradation of the sugar glucose -C 6 H 12 0 6 + 60 2 + H 2 0 + CO2 + Energy (ATP + Heat) -breakdown of glucose: exergonic having a free energy change of -686 kcal (2870 kJ) per mole of glucose decomposed -to keep working, the cell must regenerate its supply of ATP from ADP and P Redox Reactions: Oxidation and Reduction -the transfer of electrons during the chemical reactions is how the catabolic pathways decompose glucose and other organic fuels to yield energy Principle of Redox - redox reactions : transfer of one or more electrons from one reactant to another - oxidation : loss of electrons - reduction : addition of electrons -Xe - + Y X + Y e – -Xe - becomes oxidized to X
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-Y becomes reduced to Ye- QuickTime º and a decompressor are needed to see this picture. -Xe – is the electron donor, so it is the reducing agent (it reduces Y) -Y: electron acceptor so it is the oxidizing agent -not all redox rxns involve the complete transfer of electrons…some change the degree of electron sharing in covalent bonds -covalent electrosn in methane shared equally because carbon and hydrogen have equal affinity for valenece electrons…when methane reacts with oxygen and forms carbon dioxide, electrons ned up shared less equally between the carbon and the oxygen atoms (very electronegative) -O2: share their electrons equally but when oxygen reacts with the yddrogen forms water, the electrons of the covalent bonds spend more time near the oxygen (partially gained electrons)
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This note was uploaded on 03/03/2010 for the course BIOG 1101 taught by Professor N/a during the Fall '10 term at Cornell University (Engineering School).

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bio chapter 9 I - Chapter 9: Cellular Respiration Lecture...

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