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• Cellular Respiration Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Energy Transformations Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings E Transformations Thermodynamics • E flows into ecosystem as sunlight Light energy ECOSYSTEM Photosynthesis in chloroplasts CO2 + H2O Cellular respiration in mitochondria Organic molecules + O2 ATP powers most cellular work Figure 9.2 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Heat energy • Cellular respiration – Uses O2 and sugar (glucose) – Yields ATP Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • mitochondria Mitochondrion Intermembrane space Outer membrane Free ribosomes in the mitochondrial matrix Inner membrane Cristae Matrix Mitochondrial DNA Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 100 µm Overview of cellular respiration Glycolsis Glucose Pyruvate Mitochondrion ATP Substrate-level phosphorylation Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Citric acid cycle Glycolsis Glucose Pyruvate Mitochondrion ATP ATP Substrate-level phosphorylation Substrate-level phosphorylation Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Electrons carried via NADH Electrons carried via NADH and FADH2 Glycolsis Glucose Citric acid cycle Pyruvate Oxidative phosphorylation: electron transport and chemiosmosis Mitochondrion ATP Substrate-level phosphorylation ATP Substrate-level phosphorylation Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings ATP Oxidative phosphorylation • Overview of cellular respiration Electrons carried via NADH and FADH2 Electrons carried via NADH Citric acid cycle Glycolsis Pyruvate Glucose Cytosol Mitochondrion ATP Figure 9.6 Oxidative phosphorylation: electron transport and chemiosmosis Substrate-level phosphorylation Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings ATP Substrate-level phosphorylation ATP Oxidative phosphorylation • 3 main processes in metabolism Electron shuttles span membrane CYTOSOL MITOCHONDRION 2 NADH or 2 FADH2 2 NADH 2 NADH Glycolysis Glucose 2 Pyruvate 6 NADH Citric acid cycle 2 Acetyl CoA + 2 ATP by substrate-level phosphorylation Maximum per glucose: + 2 ATP 2 FADH2 Oxidative phosphorylation: electron transport and chemiosmosis + about 32 or 34 ATP by substrate-level by oxidative phosphorylation, depending on which shuttle transports electrons phosphorylation from NADH in cytosol About 36 or 38 ATP Figure 9.16 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 2 possible pathways, with and without oxygen Glucose CYTOSOL Pyruvate No O2 present Fermentation O2 present Cellular respiration MITOCHONDRION Ethanol or lactate Figure 9.18 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Acetyl CoA Citric acid cycle Evolutionary Significance of Glycolysis • Glycolysis occurs in nearly all organisms • Probably evolved before O2 in the atmosphere Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings