Chapter 9Overview: Life Is WorkSlide 3Slide 4Slide 5Concept 9.1: Catabolic pathways yield energy by oxidizing organic fuelsCatabolic Pathways and Production of ATPSlide 8Redox Reactions: Oxidation and ReductionThe Principle of RedoxSlide 11Slide 12Slide 13Slide 14Oxidation of Organic Fuel Molecules During Cellular RespirationSlide 16Slide 17Stepwise Energy Harvest via NAD+ and the Electron Transport ChainSlide 19Slide 20Slide 21The Stages of Cellular Respiration: A PreviewSlide 23Slide 24Slide 25Slide 26Slide 27Slide 28Concept 9.2: Glycolysis harvests chemical energy by oxidizing glucose to pyruvateSlide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Concept 9.3: The citric acid cycle completes the energy-yielding oxidation of organic moleculesSlide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Slide 50Slide 51Slide 52Concept 9.4: During oxidative phosphorylation, chemiosmosis couples electron transport to ATP synthesisThe Pathway of Electron TransportSlide 55Slide 56Chemiosmosis: The Energy-Coupling MechanismSlide 58Slide 59Slide 60Slide 61Slide 62Slide 63An Accounting of ATP Production by Cellular RespirationSlide 65Concept 9.5: Fermentation and anaerobic respiration enable cells to produce ATP without the use of oxygenSlide 67Types of FermentationSlide 69Slide 70Slide 71Slide 72Slide 73Fermentation and Aerobic Respiration ComparedSlide 75Slide 76The Evolutionary Significance of GlycolysisConcept 9.6: Glycolysis and the citric acid cycle connect to many other metabolic pathwaysThe Versatility of CatabolismSlide 80Slide 81Slide 82Slide 83Biosynthesis (Anabolic Pathways)Regulation of Cellular Respiration via Feedback MechanismsSlide 86Oxygen Free Radical Theory of AgingSlide 88Slide 89Slide 90Slide 91Slide 92Glucose Cross-linking with ProteinsSlide 94Slide 95Slide 96Slide 97Slide 98Slide 99You should now be able to:Slide 101Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsPowerPoint® Lecture Presentations for Biology Eighth EditionNeil Campbell and Jane ReeceLectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 9Chapter 9Cellular Respiration: Harvesting Chemical EnergyOverview: Life Is Work•Living cells require energy from outside sources•Some animals, such as the giant panda, obtain energy by eating plants, and some animals feed on other organisms that eat plantsCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsFig. 9-1•Energy flows into an ecosystem as sunlight and leaves as heat•Photosynthesis generates O2 and organic molecules, which are used in cellular respiration•Cells use chemical energy stored in organic molecules to regenerate ATP, which powers workCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsFig. 9-2LightenergyECOSYSTEMPhotosynthesis in chloroplastsCO2 + H2OCellular respirationin mitochondriaOrganicmolecules+ O2ATP powers most cellular workHeatenergyATPConcept 9.1: Catabolic pathways yield energy by oxidizing organic fuels•Several processes are central to cellular respiration and related pathwaysCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsCatabolic Pathways and Production of ATP•The breakdown of organic molecules is exergonic•Fermentation is a partial degradation of sugars that occurs without O2•Aerobic respiration consumes organic molecules and O2 and yields ATP•Anaerobic respiration is similar to aerobic respiration but consumes compounds other than O2Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings•Cellular respiration includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration•Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the sugar glucose: C6H12O6 + 6 O2  6 CO2 + 6 H2O + Energy (ATP + heat)Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsRedox Reactions: Oxidation and Reduction•The transfer of electrons during chemical reactions releases energy stored in organic molecules•This released energy is ultimately used to synthesize ATPCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsThe Principle of Redox•Chemical reactions that transfer electrons between reactants are called oxidation-reduction reactions, or redox reactions•In oxidation, a substance loses electrons, or is oxidized•In reduction, a substance gains electrons, or is reduced (the amount of positive charge is reduced)Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsFig. 9-UN1becomes oxidized(loses electron)becomes reduced(gains electron)Fig. 9-UN2becomes oxidizedbecomes reduced•The electron donor is called the reducing agent•The electron receptor is called the oxidizing agent•Some redox reactions do not transfer electrons but change the electron sharing in covalent bonds•An example is the reaction between methane and O2Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsFig. 9-3Reactantsbecomes oxidizedbecomes reducedProductsMethane(reducingagent)Oxygen(oxidizingagent)Carbon dioxide WaterOxidation of Organic Fuel Molecules During Cellular Respiration•During cellular respiration, the fuel (such as glucose) is oxidized, and O2 is reduced:Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsFig. 9-UN3becomes oxidizedbecomes reducedFig. 9-UN4DehydrogenaseStepwise Energy Harvest via NAD+ and the Electron Transport Chain•In cellular respiration, glucose and other organic molecules are broken down in a series of steps•Electrons from organic compounds are usually first transferred to NAD+, a coenzyme•As an electron acceptor, NAD+ functions as an oxidizing agent during cellular respiration•Each NADH (the reduced form of NAD+) represents stored energy that is tapped to synthesize ATPCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsFig. 9-4DehydrogenaseReduction of NAD+Oxidation of NADH2 e– + 2 H+2 e– + H+NAD++2[H]NADH+H+H+Nicotinamide(oxidized form)Nicotinamide(reduced form)•NADH passes the electrons to the electron transport chain•Unlike an uncontrolled reaction, the electron transport chain passes electrons in a series of steps instead of one explosive reaction•O2 pulls electrons down the chain