Chapter 9 Cellular Respiration Harvesting Chemical Energy PowerPoint Lectures for Biology Eighth Edition Neil Campbell and Jane Reece Energy Light energy Flows into an ecosystem as sunlight and leaves as heat ECOSYSTEM Photosynthesis in chloroplasts CO2 H2O Cellular respiration in mitochondria Organic molecules ATP powers most cellular work Figure 9 2 Heat energy O2 Redox Reactions Oxidation and Reduction In oxidation OIL A substance loses electrons or is oxidized In reduction RIG A substance gains electrons or is reduced Examples of redox reactions becomes oxidized loses electron Na Cl Na becomes reduced gains electron Cl Oxidation of Organic Fuel Molecules During Cellular Respiration During cellular respiration Glucose is oxidized and oxygen is reduced becomes oxidized C6H12O6 6O2 6CO2 6H2O Energy becomes reduced Stepwise Energy Harvest via NAD and the Electron Transport Chain Electrons from organic compounds Are usually first transferred to NAD a coenzyme 2e 2H NAD 2 e H Dehydrogenase O H C NH2 O CH2 O N Nicotinamide oxidized form O P O O H H OH O P O HO CH2HO O N H O H HO N H OH 2 H from food Oxidation of NADH H H O C NH2 N Nicotinamide reduced form NH2 N N Reduction of NAD NADH H Figure 9 4 If electron transfer is not stepwise A large release of energy occurs As in the reaction of hydrogen and oxygen to form water Free energy G H2 1 2 O2 Figure 9 5 A Explosive release of heat and light energy H2O a Uncontrolled reaction 2H 1 2 O2 from food via NADH tr Elec a on tr ATP ATP rt ch nspo Free energy G 2 H 2 e Controlled release of energy for synthesis of ATP ATP ain 2 e 2H 2 O2 1 H2O Figure 9 5 B b Cellular respiration The Stages of Cellular Respiration A Preview Respiration is a cumulative function of three metabolic stages Glycolysis The citric acid cycle Oxidative phosphorylation C6H12O6 6 O2 electron transport chain 6 CO2 6 H2O Energy ATP Heat An overview of cellular respiration Electrons carried via NADH and FADH2 Electrons carried via NADH Glucos e Glycolsis Pyruvate Cytosol ATP Figure 9 6 Substrate level phosphorylation Citric acid cycle Oxidative phosphorylation electron transport and chemiosmosis Mitochondrion ATP Substrate level phosphorylation ATP Oxidative phosphorylation energy investment phase energy payoff phase Glycolysis Citric Oxidative acid cycle phosphorylation 2 NADH 2 H 2 Glucose ATP ADP P CH2 O P 1 3 Bisphosphoglycerate 2 ADP 7 Phosphoglycerokinase Hexokinase 2 ATP 2 CH2 O P 3 Phosphoglycerate 8 Phosphoglyceromutase Phosphoglucoisomerase CH2O P O CH2OH H HO HO H HO H 2 O C Fructose 6 phosphate O H C O 3 ADP 2 P O CH2 O CH2 O P HO H OH HO H O C O C O P CH2 Phosphoenolpyruvate 2 ADP 10 4 Pyruvate kinase 2 ATP 5 H P O CH2 Isomerase C O C O CHOH CH2OH CH2 O P Dihydroxyacetone phosphate Glyceraldehyde3 phosphate P CH2OH 2 Phosphoglycerate 9 Enolase 2 H 2O Phosphofructokinase Aldolase O C CHOH Glucose 6 phosphate 2 Fructose1 6 bisphosphate O C O CHOH 1 CH2OH P HH OH OH H HO H OH ATP 6 Triose phosphate dehydrogenase 2 Pi 2 NAD CH2OH HH H HO H HO OH H OH 2 O C O C O Figure 9 9 A Figure 9 8 B CH3 Pyruvate Glycolysis Overview Glycolysis ATP Oxidative phosphorylation Citric acid cycle ATP ATP Energy investment phase Glucose 2 ATP Invested 2 ATP 2 P 2 ATP used Energy payoff phase 4 ATP generated 4 ADP 4 P 2 NAD reduced to 2 NADH 2 NAD 4 e 4 H 2 NADH Net Products at end of Glycolysis 2 pyruvate molecules 2 ATP 2 H 2 Pyruvate 2 H2O Glucose 4 ATP formed 2 ATP used 2 NAD 4 e 4 H 2 NADH formed 4 ATP 2 Pyruvate 2 H2O 2 ATP 2 H 2 NADH Figure 9 8 Intermediate Step Between Glycolysis and Citric Acid Cycle Before the citric acid cycle can begin Pyruvate must first be converted to acetyl CoA which links the cycle to glycolysis CYTOSOL This Step Yields per pyruvate 1 CO2 MITOCHONDRION NAD NADH H O CoA C O 2 C C O O 1 NADH 1 3 CH3 Pyruvate Transport protein Figure 9 10 S CH3 Acetyle CoA CO2 Coenzyme A A closer look at the citric acid cycle Glycolysis Citric Oxidative acid phosphorylation cycle S CoA C O CH3 Acetyl CoA CoA SH O NADH H C COO CH2 1 CH2 COO NAD 8 Oxaloacetate HO C COO CH2 COO CH2 COO HO CH H2 O COO CH2 2 HC COO COO Malate HO Citrate COO Isocitrate COO H2 O Citric acid cycle 7 COO CH CO2 3 NAD COO Fumarate HC CH2 CoA SH CH2 COO 6 CoA SH COO CH2 FADH2 FAD COO CH2 C O COO Pi S CoA GTP GDP Succinyl CoA ADP ATP 4 COO NAD NADH H NADH H Ketoglutarate C O CH2 5 CH2 Succinate Figure 9 12 CH CO2 An overview of the citric acid cycle Pyruvate from glycolysis 2 molecules per glucose Glycolysis Citric acid cycle ATP ATP Oxidative phosphorylation ATP CO2 CoA Net Products from Intermediate Step Citric Acid Cycle NADH 3 H Acetyle CoA CoA CoA 2 ATP 6 CO2 8 NADH 2 FADH2 FADH2 Citric acid cycle FAD 2 CO2 3 NAD 3 NADH 3 H ADP P i ATP Figure 9 11 The Pathway of Electron Transport At the end of the chain Electrons are passed to oxygen forming water 50 NADH Free energy G relative to O2 kcl mol FADH2 40 I Fe S 30 20 Multiprotein complexes FAD Fe S II O III Cyt b Fe S Cyt c1 IV Cyt c Cyt a Cyt a3 10 0 Figure 9 13 FMN 2 H 1 2 O 2 H2O Chemiosmosis and the electron transport chain Oxidative phosphorylation electron transport and chemiosmosis Glycolysis ATP Inner Mitochondrial membrane ATP ATP H H H Intermembrane space Protein complex of electron carners Q I Inner mitochondrial membrane Figure 9 15 IV III II FADH2 NADH Mitochondrial matrix H Cyt c NAD FAD 2 H 1 2 O2 ATP synthase H2O ADP Carrying electrons from food ATP Pi H Chemiosmosis Electron transport chain ATP synthesis powered by the flow Electron transport and pumping of protons H which create an H gradient across the membrane Of H back across the membrane Oxidative phosphorylation Chemiosmosis The Energy Coupling Mechanism ATP synthase Is the enzyme that actually makes ATP INTERMEMBRANE SPACE H H H H H H H A stator anchored in the membrane holds the knob stationary H ADP Pi Figure 9 14 MITOCHONDRIAL MATRIX A rotor within the membrane spins clockwise when H flows past it down the H gradient ATP A rod for stalk extending into the knob also spins activating catalytic sites in the knob Three catalytic sites in the stationary knob join inorganic Phosphate to ADP to make ATP Cellular Respiration Review There are three main processes in this metabolic enterprise Electron shuttles span membrane CYTOSOL MITOCHONDRION 2 NADH or 2 FADH2 2 NADH 2 NADH Glycolysis …
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