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Oxidation, Reduction, and Energy Cellular Respiration Today s topics Catabolic Oxidation of Glucose • Glycolysis – Oxidation of glucose to pyruvate • Mitochondria – Structure and function • It time: Citric Acid Cycle – Oxidation of pyruvate to CO2 7 October 2016 1 Proteins Carbohydrates General Catabolic Pathway • Amino acids Sugars Fats Glycerol Fatty acids Step down the oxidation series of carbon in a series of small Steps Glycolysis Some activation step Glucose Oxidation step, with energy harvest Reorganization step Another oxidation step, another harvest Another reorganization etc. etc. Glyceraldehyde-3- P NH3 Acetyl CoA Citric acid cycle yield product of pathway 3 Glycolysis: 6 carbon sugar Figure 9.19 Steps in the oxidation of glucose Glucose For each step: What goes in? What comes out? Where does it happen? Harvest ATP and NADH oxidized to pyruvate Pyruvate Oxidative phosphorylation 4 In Cytoplasm In Mitochondrial Matrix Keep track of the carbon atoms. (Two) 3 carbon acids 5 Keep track of the energy molecules. On Inner Mitochondrial membrane 1 Glycolysis Summary 6-Carbon Sugar à 2x 3-Carbon Acids Substrate-level Phosphorylation Energy harvest phase Energy investment phase 8 7 H Glycolysisthe details HO CH2OH H H HO H OH OH H Glucose ATP 1 Hexokinase ADP NAD+ is an electron carrier Energy Investment Stage Add P to #6 carbon CH2OH P O H H H OH H HO H OH Glucose-6-phosphate Rearrange 2 Phosphoglucoisomerase CH2O P O CH2OH H HO HO H HO H Fructose-6-phosphate (see also NADP+ and FAD) Split into two 3 carbon units Rearrange Do Not Memorize! 3 ATP Add P to #1 carbon Phosphofructokinase ADP P O CH2 O CH2 O HO H OH HO H Fructose1, 6-bisphosphate 4 Aldolase P O CH2 C 5 H Isomerase O CH2OH Dihydroxyacetone phosphate Figure 9.9 A Oxidize aldehyde to acid add another phosphate Harvest NADH P 2 of these C O CHOH CH2 O P 10 Glyceraldehyde3-phosphate 6 2 X Glyceraldehyde-3-P Pi NADH Net Result of Glycolysis + 2 H+ 2 P O C O CHOH P CH2 O 1, 3-Bisphosphoglycerate Make ATP by Substrate Level Phosphorylation 7 ATP Glycolysis Energy payoff this pathway happens twice for each glucose O– 2 O C CHOH O CH2 3-Phosphoglycerate – # ATP: P 8 Rearrange O– 2 C H C O – # eletron carriers: P O CH2OH 2-Phosphoglycerate 9 Oxidize alcohol to ketone Enolase 2 H2O 2 Make ATP by Substrate Level Phosphorylation O– C O C O P CH2 Phosphoenolpyruvate 10 ATP Do Not Memorize! 2 Pyruvate x2 Figure 9.8 B O– C O C O 11 12 CH3 2 Figure 9.6-3 What happens to the products of glycolysis? Mitochondrion Electrons carried via NADH and FADH2 Electrons carried via NADH Matrix Pyruvate oxidation Glycolysis Glucose Acetyl CoA Pyruvate Oxidative phosphorylation: electron transport and chemiosmosis Citric acid cycle Inner Membrane MITOCHONDRION CYTOSOL ATP Substrate-level phosphorylation Substrate-level phosphorylation Proteins Carbohydrates Amino acids Sugars Outer Membrane ATP ATP Oxidative phosphorylation Intermembrane Space 14 Fats Glycerol Pyruvate oxidation Fatty acids Glycolysis Glucose Glyceraldehyde-3- P NH3 Pyruvate Acetyl CoA Citric acid cycle Oxidative phosphorylation 15 Net Result of Citric Acid Cycle and pyruvate oxidation • Pyruvate oxidation to acetyl-CoA – # ATP: – # electron carriers: • Citric acid cycle: – # ATP: – # electron carriers: 18 3