Cellular Respiration Copyright 2005 Pearson Education Inc publishing

• 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 CO 2 + H 2 O Cellular respiration in mitochondria Organic molecules + O 2 ATP powers most cellular work Figure 9. 2 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Heat energy

• Cellular respiration – Uses O 2 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 Substrate-level phosphorylation Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Electrons carried via NADH and FADH 2 Glycolsis Glucose Citric acid cycle Pyruvate Oxidative phosphorylation: electron transport and chemiosmosis Mitochondrion 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 FADH 2 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 FADH 2 2 NADH Glycolysis Glucose 2 Pyruvate 6 NADH Citric acid cycle 2 Acetyl Co. A + 2 ATP by substrate-level phosphorylation Maximum per glucose: + 2 ATP 2 FADH 2 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 O 2 present Fermentation O 2 present Cellular respiration MITOCHONDRION Ethanol or lactate Figure 9. 18 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Acetyl Co. A Citric acid cycle

Evolutionary Significance of Glycolysis • Glycolysis occurs in nearly all organisms • Probably evolved before O 2 in the atmosphere Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings