Course Notes > University of Louisville BIO 240ch 9 cellular respiration and fermentation notes

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University of Louisville BIO 240 ch 9 cellular respiration and fermentation notes Cellular Respiration and Fermentation  Catabolic Pathways yield energy by oxidizing organic fuels o Several pr... ocesses are central to cellular respiration and related pathways o The breakdown of organic molecules is exergonic o Fermentation is a partial degradation of sugars that occur without O2 o Aerobic Respiration consumes molecules and O2 to make ATP o Cellular Respiration includes both aerobic and anaerobic processes  Redox Reactions = Oxidation and Reduction o Oxidation - loses electrons o Reduction - accepts electrons o The electron donor is called the reducing agent o The electron acceptor is called the oxidizing agent o NADP+ - electron carrier in respiration  3 Stages of Cellular Respiration (Figure 9.6) o Glycolysis  3 phases of Glycolysis  Energy Investment Phase  Hexokinase transfers a phosphate group from ATP to glucose, making it more chemically reactive. The charge of the phosphate also traps the sugar in the cell  Glucose 6-Phosphate is converted to its isomer, Fructose 6-Phosphate  Phosphofructokinase transfers a phosphate group from ATP to the opposite end of the sugar, investing a second molecule of ATP. This is a key step for regulation of glycolysis.  Aldolase cleaves the sugar molecule into two different three-carbon sugars (isomers).  Isomerase catalyzes the reversible conversion between the two isomers. This reaction never reaches equilibrium: Glyceraldehyde 3-Phosphate is used as the substrate of the next reaction as fast as it forms.  Energy Payoff Phase  The enzyme catalyzes two sequential reactions. First, the sugar is oxidized by the transfer of elctrons to NAD+, forming NADH  Net  Oxidates  Creates 4 ATP, but uses 2 => Net 2 ATP  Sugar-breakdown  Glucose -> Pyruvate  Glucose is cut in half  Producing NADH  From the cytosol, it then moves to the matrix of the mitochondria for…. o Pyruvate Oxidation and the Citric Acid/Krebs Cycle  Makes ATP  Decarboxylation  During Oxidative Phosphorylation, Chemiosmosis couples electron transport to ATP synthesis [Show More]

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