Chapter 7 Cellular Respiration Organic molecules O 2 CO 2 H2O Energy Part 1 Aerobic Respiration 4 Steps of Glucose Metabolism Fig 7 4 I Step 1 Glycolysis A Performed by almost all organisms B Doesn t require O2 C Occurs in cytosol D Breaks glucose in half C6 2 C3 1 1 glucose 2 pyruvate E Net gain of 2 ATP 2 NADH H F 10 steps in 3 phases 1 Energy Investment Phase a Glucose Enzyme 2ATP 6 Carbon compound 2 ADP 2 Cleavage Phase a 6 Carbon compound 2 G3P a 2 G3P 2 molecules of 3 Energy Liberation Phase pyruvate 4 ATP 2 NADH G NADH Redox Reactions 2e H redox NADH 1 NAD rxn a NAD reduced gains energy Pyruvate oxidized loses energy b NADH is an energy intermediate 2 Redox Reactions a Oxidized molecules tend to lose H i Tend to have C O bonds not C H nonds ii Follow H to follow electrons H ATP in glycolysis is generated by an enzyme substrate level phosphorylation 1 Phosphoenolpyruvate 1 phosphorous and ADP combine on an enzyme to form ATP pyruvate I Pyruvate is transported into mitochondria breakdown continues II Step 2 Pyruvate Breakdown Acetyl Co A Synthesis Fig 7 6 A Pyruvate dehydrogenase removes CO2 from 3 C pyruvate B 2 C acetyl combines with CoA C Per pyruvate 1 acetyl CoA 1 NADH 1 CO2 III Step 3 Citric Acid Cycle Krebs Cycle Fig 7 7 A Each acetyl group is oxidized to 2 CO2 B Acetyl 2 C removed attatched to oxaloacetate 4 C Citrate 6 C C Cycle releases 2 CO2 1 ATP 3NADH 1 FADH2 D Oxaloacetate is regenerated E Regenrates high energy compounds by incorporating then breaking down acetyl group see Fig 7 7 Breakdown of 1 glucose so far Process Glycolysis Pyruvate breakdown Krebs Total ATP 2 2 4 NADH 2 2 6 10 HADH2 2 2 CO2 2 4 6 Other 2 Pyruvate 2 Acetyl CoA IV Oxidative Phosphorylation Electron Transport Chain ATP Synthesis A Uses NADH FADH2 to make ATP B Oxidative Phosphorylation includes the ETC phosphorylation of ADP via ATP Synthase 1 Electron Transport Chain a Composed proteins or small organic molecules b Accept release electrons in a series of redox reactions c Electrons lose energy as they move through ETC d Electron movement generates H electrochemical gradient proton motive force C Process of Oxidative Phosphorylation 1 NADH donates electrons to complex I complex I accepts them pumps H across membrane 2 FADH2 transfers electrons to complex II 3 Electrons move to CoQ Or U for ubiquinone forming CoQH2 4 Electrons donated from CoQH2 to complex III H pumped across membrane a H accumulating on bottom of diagram inside making acidic environment b Protons H being pumped across membrane at complex I complex III so far 5 Electrons transferred to Cc 6 Electron transferred to IV IV pumps H across the membrane and transfers electrons to the final electron acceptor an oxygen atom resulting in H2O formation electron transport chain ends a Products of electron transport chain H2O the H gradient 7 H gradient used by ATP synthase to make ATP Matrix Intermembrane Space V Summary of Aerobic Eukaryotic Respiration A NADH FADH2 donate electrons B Oxygen atom is the ultimate electron acceptor C Electron movement is highly exergonic D Complexes I III IV use energy from exergonic electron movement to pump H into intermembrane space E ATP synthase uses H gradient to power ATP synthesis F Respiration breaks down fats proteins also 1 Fats proteins enter the catabolic pathway at different places G Summary Diagrams Some prokaryotes also produce ATP through oxidative phosphorylation use plasma membrane for ETC instead of mitochondrial membrane Part 2 Anaerobic Respiration Fermentation in Humans I Fermentation A Breakdown of organic molecules to produce energy without any net oxidation in the system B May use organic or inorganic electron acceptor C Produces less ATP than aerobic metabolism A Pyruvate from glycolysis NADH H lactic acid NAD II Fermentation in Humans
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