1. © 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey Chapter 6 How Cells Harvest Chemical Energy

2. Figure 6.0_1 Chapter 6: Big Ideas Cellular Respiration: Aerobic Harvesting of Energy Stages of Cellular Respiration Fermentation: Anaerobic Harvesting of Energy Connections Between Metabolic Pathways

3. CELLULAR RESPIRATION: AEROBIC HARVESTING OF ENERGY © 2012 Pearson Education, Inc.

4. Figure 6.1_1 Sunlight energy ECOSYSTEM Photosynthesis in chloroplasts Cellular respiration in mitochondria (for cellular work) Heat energy Glucose CO 2 H2OH2O O2O2 ATP

5. Cellular Respiration  Summary Equation: © 2012 Pearson Education, Inc. Glucose OxygenWater Carbon dioxide C 6 H 12 O 6 O2O2 H2OH2O ATP6 6 6  Heat CO 2  Cellular respiration is an exergonic process  Transfers energy from the bonds in glucose to form ATP.  produces up to 32 ATP molecules from each glucose molecule

6. Figure 6.2_1 Breathing Lungs Bloodstream CO 2 Muscle cells carrying out Cellular Respiration Glucose  O 2 CO 2  H 2 O  ATP CO 2 O2O2 O2O2

7. Figure 4.13 Matrix Cristae Inner membrane Outer membrane Mitochondrion Intermembrane space

8. Cellular Respiration is a Redox Process  Electrons from glucose are slowly harvested and transferred to two different electron carriers: –NAD+ and FAD –NAD+ reduced to NADH; FAD reduced to FADH 2  These electrons are then used to generate ATP by and electron transport chain and chemiosmosis © 2012 Pearson Education, Inc. Glucose  Heat C 6 H 12 O 6 O2O2 CO 2 H2OH2O ATP 6 6 6 Loss of hydrogen atoms (becomes oxidized) Gain of hydrogen atoms (becomes reduced)

9. Figure 6.5B Becomes oxidized Becomes reduced 2H NAD  NADH HH HH 2 2 (carries 2 electrons)

10. Figure 6.5C Controlled release of energy for synthesis of ATP NADH NAD  HH HH O2O2 H2OH2O 2 2 2 ATP Electron transport chain 2 1

11. STAGES OF CELLULAR RESPIRATION © 2012 Pearson Education, Inc.

12. Cellular respiration occurs in three main stages  Stage 1 – Glycolysis –Cytoplasm –Converts glucose to pyruvate  Stage 2 – Pyruvate oxidation and citric acid cycle –Mitochondrial matrix –Pyruvate oxidation: oxidizes pyruvate to acetyl-CoA; generates NADH –TCA: acetyl-CoA oxidized to CO 2 ; generates NADH and FADH 2  Stage 3 – Oxidative phosphorylation (pay-off phase) –Inner membrane of mitochondria –Produces ATP by chemiosmosis © 2012 Pearson Education, Inc.

13. Figure 6.6 NADH FADH 2 ATP CYTOPLASM Glycolysis Electrons carried by NADH Glucose Pyruvate Pyruvate Oxidation Citric Acid Cycle Oxidative Phosphorylation (electron transport and chemiosmosis) Mitochondrion Substrate-level phosphorylation Oxidative phosphorylation

14. Stage 1: Glycolysis occurs in the CYTOPLASM © 2012 Pearson Education, Inc. 1 Glucose + 2 ATP + 2 NAD+ + 4 ADP + 4 P 2 Pyruvate + 2 ADP + 2 P + 2 NADH + 4 ATP  Net Gain: 2 ATP, 2 NADH, 2 Pyruvate  NO O 2 required - Anaerobic process  NO CO 2 yet released - All carbons from original glucose still accounted for  All living organisms able to use glycolysis stage to gain 2 ATP from glucose!!

15. Figure 6.7Ca_s2 Glucose Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Glyceraldehyde 3-phosphate (G3P) ENERGY INVESTMENT PHASE P P PP P P ADP ATP Step Steps – A fuel molecule is energized, using ATP. Step A six-carbon intermediate splits into two three-carbon intermediates. 44 3 3 2 11

16. Figure 6.7Cb_s2 6 66555 9 998877 Step A redox reaction generates NADH. Steps – ATP and pyruvate are produced. ENERGY PAYOFF PHASE 1,3-Bisphospho- glycerate 3-Phospho- glycerate 2-Phospho- glycerate Phosphoenol- pyruvate (PEP) Pyruvate NADH NAD  HH HH ADP ATP H2OH2O H2OH2O P P P P P P P P P P P P P P

17. Figure 6.7A Glucose 2 Pyruvate 2 ADP 2 P 2 NAD  2 NADH 2 H  ATP 2  ATP is formed in glycolysis by substrate- level phosphorylation during which –Direct transfer of P from one molecule to ADP

18. Figure 6.6_1 NADH FADH 2 ATP CYTOPLASM Glycolysis Electrons carried by NADH Glucose Pyruvate Pyruvate Oxidation Citric Acid Cycle Oxidative Phosphorylation (electron transport and chemiosmosis) Mitochondrion Substrate-level phosphorylation Oxidative phosphorylation

19. Stage 2: Pyruvate Oxidation and The Citric Acid Cycle Occurs in the mitochondrial matrix  Pyruvate Oxidation –The pyruvate formed in glycolysis is transported from the cytoplasm into mitochondrial matrix (NOTE: Only IF O 2 present) –Two molecules of pyruvate are produced for each molecule of glucose that enters glycolysis. Pyruvate Coenzyme A Acetyl coenzyme A NAD  NADHHH CoA CO 2 3 2 1

20. © 2012 Pearson Education, Inc. Stage 2: Carbons Enter TCA cycle As Acetyl- CoA  For each acetyl-CoA that enters the TCA cycle: –the two-carbon group of acetyl CoA is added to a four- carbon compound called oxaloacetate, forming citrate –citrate is degraded back to the four-carbon compound, –two CO 2 are released, and –1 ATP, 3 NADH, and 1 FADH 2 are produced.

21. Figure 6.9A Acetyl CoA Citric Acid Cycle CoA CO 2 2 3 3 NAD  3 H  NADH ADP ATP P FAD FADH 2

22. Figure 6.9B_s1 CoA 1 Acetyl CoA Oxaloacetate Citric Acid Cycle 2 carbons enter cycle Step Acetyl CoA stokes the furnace. 1

23. Figure 6.9B_s2 NADH NAD  HH HH CO 2 ATP ADP P CoA 321312 Acetyl CoA Oxaloacetate Citric Acid Cycle 2 carbons enter cycle Citrate leaves cycle Alpha-ketoglutarate leaves cycle Step Acetyl CoA stokes the furnace. Steps – NADH, ATP, and CO 2 are generated during redox reactions.

24. Figure 6.9B_s3 NADH NAD  NADH HH HH HH CO 2 ATP ADP P FAD FADH 2 CoA 3214534512 Acetyl CoA Oxaloacetate Citric Acid Cycle 2 carbons enter cycle Citrate leaves cycle Alpha-ketoglutarate leaves cycle Succinate Malate Step Acetyl CoA stokes the furnace. Steps – NADH, ATP, and CO 2 are generated during redox reactions. Steps – Further redox reactions generate FADH 2 and more NADH.

25. Energy Accounting (per glucose)  Glycolysis: 2 NADH; 2 ATP  Pyruvate oxidation: 2 NADH  TCA: 2 ATP, 6 NADH, and 2 FADH 2.  Sum Total: –4 ATP –10 NADH –2 FADH 2 © 2012 Pearson Education, Inc.

26. Stage 3: Oxidative Phosphorylation uses electron transport chain and ATP synthase embedded in inner membrane  Stage 3: Oxidative phosphorylation (ETC) –Pay-off phase!! (Get 28 ATPs) –Electrons carried by NADH and FADH 2 are deposited into ETC to generate ATP by chemiosmosis. –Each NADH = 2.5 ATPs (x10 = 25 ATP) –Each FADH 2 = 1.5 ATPs (x2 = 3 ATP) –O 2 required as final electron acceptor!!!! © 2012 Pearson Education, Inc.

27. 6.10 Most ATP production occurs by oxidative phosphorylation  Electrons from NADH and FADH 2 travel down the electron transport chain to O 2.  Oxygen picks up H + to form water.  Energy released by these redox reactions is used to pump H + from the mitochondrial matrix into the intermembrane space.  In chemiosmosis, the H + diffuses back across the inner membrane through ATP synthase complexes, driving the synthesis of ATP. © 2012 Pearson Education, Inc.

28. Figure 6.10 Oxidative Phosphorylation Electron Transport Chain Chemiosmosis Mito- chondrial matrix Inner mito- chondrial membrane Intermem- brane space Electron flow Protein complex of electron carriers Mobile electron carriers ATP synthase NADH NAD  2 H  FADH 2 FAD O2O2 H2OH2O ADP PATP 1 2 HH HH HH HH HH HH HH HH HH HH HH I II III IV

30. Figure 6.11 ATP synthase NAD  NADH FADH 2 FAD HH HH HH HH HH HH HH HH 2 H  H2OH2O ADP ATP P O2O2 2 1 Rotenone Cyanide, carbon monoxide Oligomycin DNP

31. Figure 6.12 NADH FADH 2 NADH FADH 2 NADH or NADH Mitochondrion CYTOPLASM Electron shuttles across membrane Glycolysis Glucose 2 Pyruvate Pyruvate Oxidation 2 Acetyl CoA Citric Acid Cycle Oxidative Phosphorylation (electron transport and chemiosmosis) Maximum per glucose: by substrate-level phosphorylation by oxidative phosphorylation 2 2 2 2 62 ATP  2 about  28 ATP About ATP32ATP  2