1. Ch 9 Cellular Respiration Extracting usable energy from organic molecules

2. Energy flows into ecosystems as sunlight Photosynthesis generates organic molecules and O 2. Cellular respiration breaks down organic molecules to generate ATP;uses O 2. ------>fuels cellular activities

3. LE 9-2 ECOSYSTEM Light energy Photosynthesis in chloroplasts Cellular respiration in mitochondria Organic molecules + O 2 CO 2 + H 2 O ATP powers most cellular work Heat energy

4. If eukaryotes have mitochondria are they capable of of aerobic respiration? Does this include protists, fungi, plants and animals? You bet!

5. C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + ATP Cellular Respiration Net Reaction: Redox reaction C 6 H 12 O 6 oxidized to CO 2 O 2 reduced to H 2 O glucoseEnergy molecule

6. Is cellular respiration endergonic or exergonic? Anabolic or catabolic? Exergonic (exothermic) Catabolic (breaks down molecules to release energy)

7. LE 9-6_1 Mitochondrion Glycolysis Pyruvate Glucose Cytosol ATP Substrate-level phosphorylation Cytosol Matrix Inner membrane Outer membrane Cristae Mitochondrion Intermembrane space

8. Three major steps in cellular respiration 1. Glycolysis: the breaking of sugar 2. Citric acid cycle (Krebs Cycle) 3. Oxidative phosphorylation In cytosol In mitochondria

9. LE 9-6_1 Mitochondrion Glycolysis Pyruvate Glucose Cytosol ATP Substrate-level phosphorylation

10. Glycolysis 6C organic molecule-->--> 2(3C) organic molecule 1 glucose --> 2 pyruvates Is the conversion of glucose to pyruvate a simple one step process? NO Requires 10 enzyme catalyzed reactions!

11. LE 9-9a_1 Glucose ATP ADP Hexokinase ATP Glycolysis Oxidation phosphorylation Citric acid cycle Glucose-6-phosphate

12. LE 9-9a_2 Glucose ATP ADP Hexokinase ATP Glycolysis Oxidation phosphorylation Citric acid cycle Glucose-6-phosphate Phosphoglucoisomerase Phosphofructokinase Fructose-6-phosphate ATP ADP Fructose- 1, 6-bisphosphate Aldolase Isomerase Dihydroxyacetone phosphate Glyceraldehyde- 3-phosphate

13. LE 9-9b_1 2 NAD + Triose phosphate dehydrogenase + 2 H + NADH 2 1, 3-Bisphosphoglycerate 2 ADP 2 ATP Phosphoglycerokinase Phosphoglyceromutase 2-Phosphoglycerate 3-Phosphoglycerate

14. LE 9-9b_2 2 NAD + Triose phosphate dehydrogenase + 2 H + NADH 2 1, 3-Bisphosphoglycerate 2 ADP 2 ATP Phosphoglycerokinase Phosphoglyceromutase 2-Phosphoglycerate 3-Phosphoglycerate 2 ADP 2 ATP Pyruvate kinase 2 H 2 O Enolase Phosphoenolpyruvate Pyruvate

15. LE 9-8 Energy investment phase Glucose 2 ATP used 2 ADP + 2 P 4 ADP + 4 P 4 ATP formed 2 NAD + + 4 e – + 4 H + Energy payoff phase + 2 H + 2 NADH 2 Pyruvate + 2 H 2 O 2 ATP 2 NADH + 2 H + Glucose 4 ATP formed – 2 ATP used 2 NAD+ + 4 e – + 4 H + Net Glycolysis Citric acid cycle Oxidative phosphorylation ATP

16. What is NAD + ? An electron carrier NAD + + e- + H- --> NADH

17. LE 9-6_2 Mitochondrion Glycolysis Pyruvate Glucose Cytosol ATP Substrate-level phosphorylation ATP Substrate-level phosphorylation Citric acid cycle 2. Citric acid cycle ( aka Krebs cycle)

18. Reactions in the Mitochondrion Conversion of pyruvate (3C) to acetyl coA (2C) In what compartment? Matrix

19. LE 9-10 CYTOSOL Pyruvate NAD + MITOCHONDRION Transport protein NADH + H + Coenzyme ACO 2 Acetyl Co A

20. LE 9-11 Pyruvate (from glycolysis, 2 molecules per glucose) ATP Glycolysis Oxidation phosphorylation Citric acid cycle NAD + NADH + H + CO 2 CoA Acetyl CoA CoA Citric acid cycle CO 2 2 3 NAD + + 3 H + NADH3 ATP ADP + P i FADH 2 FAD e- carrier Where is this pathway taking place?

21. Third step Oxidative phosphorylation 1. Electron transport chain 2. Chemiosmosis In what compartment? Inner mitochondrial membrane

22. LE 9-13 ATP Glycolysis Oxidative phosphorylation: electron transport and chemiosmosis Citric acid cycle NADH 50 FADH 2 40 FMN FeS I FAD FeS II III Q FeS Cyt b 30 20 Cyt c Cyt c 1 Cyt a Cyt a 3 IV 10 0 Multiprotein complexes Free energy (G) relative to O2 (kcal/mol) H2OH2O O2O2 2 H+ + 1 / 2 Oxygen final e- acceptor, most electronegative

23. LE 9-15 Protein complex of electron carriers ATP Glycolysis Oxidative phosphorylation: electron transport and chemiosmosis Citric acid cycle Q III I II FAD FADH 2 + H+ NADH NAD + (carrying electrons from food) Inner mitochondrial membrane Mitochondrial matrix Intermembrane space Cyt c IV 2H + + 1 / 2 O 2 H2OH2O ADP + ATP synthase Electron transport chain Pumping of protons (H+), creates H+ gradient across the membrane P i Chemiosmosis ATP synthesis powered by diffusion of H+ into matrix Oxidative phosphorylation H+

24. LE 9-14 INTERMEMBRANE SPACE H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP MITOCHONDRAL MATRIX ADP + P i A rotor within the membrane spins as shown when H + flows past it down the H + gradient. A stator anchored in the membrane holds the knob stationary. A rod (or “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.

25. LE 9-16 CYTOSOL Electron shuttles span membrane 2 NADH or 2 FADH 2 MITOCHONDRION Oxidative phosphorylation: electron transport and chemiosmosis 2 FADH 2 2 NADH6 NADH Citric acid cycle 2 Acetyl CoA 2 NADH Glycolysis Glucose 2 Pyruvate + 2 ATP by substrate-level phosphorylation + 2 ATP by substrate-level phosphorylation + about 32 or 34 ATP by oxidation phosphorylation, depending on which shuttle transports electrons from NADH in cytosol About 36 or 38 ATP Maximum per glucose: 3 ATP/NADH 2 ATP/ FADH2

26. Fermentation production of ATP anaerobically (without O 2 ) How? Glycolysis only (fermentation)

27. Two fermentation pathways –alcohol fermentation –lactic acid fermentation

28. LE 9-18 Pyruvate Glucose CYTOSOL No O 2 present Fermentation Ethanol or lactate Acetyl CoA MITOCHONDRION O 2 present Cellular respiration Citric acid cycle

29. LE 9-17a CO 2 + 2 H + 2 NADH2 NAD + 2 Acetaldehyde 2 ATP 2 ADP + 2 P i 2 Pyruvate 2 2 Ethanol Alcohol fermentation Glucose Glycolysis

30. LE 9-17b CO 2 + 2 H + 2 NADH2 NAD + 2 ATP 2 ADP + 2 P i 2 Pyruvate 2 2 Lactate Lactic acid fermentation Glucose Glycolysis

31. Under what circumstances does anaerobic respiration or fermentation occur? In O 2 -starved muscles accumulation of lactic acid painful: toxic In some micro-organisms: bacteria, yeast exploited for production of alcoholic beverages cheeses

32. Evolutionary Significance of Glycolysis Glycolysis occurs in nearly all organisms May have evolved in ancient prokaryotes before oxygen in atmosphere

33. Regulation of ATP synthesis Negative and positive feedback loops

34. LE 9-20 Citric acid cycle Oxidative phosphorylation Glycolysis Glucose Pyruvate Acetyl CoA Fructose-6-phosphate Phosphofructokinase Fructose-1,6-bisphosphate – Inhibits ATP Citrate Inhibits Stimulates AMP + –

35. The Versatility of Catabolism Catabolic pathways – funnel electrons from many organic molecules into cellular respiration Glycolysis – accepts wide range of carbohydrates Proteins –digested to amino acids; amino groups feed glycolysis or the citric acid cycle Fats –digested to glycerol (used in glycolysis) and fatty acids (used in generating acetyl CoA)

36. LE 9-19 Citric acid cycle Oxidative phosphorylation Proteins NH 3 Amino acids Sugars Carbohydrates Glycolysis Glucose Glyceraldehyde-3- P Pyruvate Acetyl CoA Fatty acids Glycerol Fats