Aerobic Respiration

1. Aerobic Respiration Section 9:2

2. Aerobic Respiration – Oxygen Present • Occurs in the mitochondria of eukaryotes and the cytosol of prokaryotes. • Pyruvic acid, from Glycolysis, diffuses in from the cytosol to the mitochondrial matrix. • The space inside the inner membranes

3. inner compartment outer compartment cytoplasm outer mitochondrial membrane inner mitochondrial membrane (see next slide) Fig. 7.5a, p. 114

6. Krebs Cycle • A biochemical pathway that breaks down a compound acetyl CoA, producing CO2, NADH, FADH, ATP and Citric Acid, in the mitochondria. • 5 steps to the Krebs Cycle

7. Aerobic Respiration – before Krebs Cycle (reparatory step) • Pyruvic acid joins with Coenzyme A (CoA), no carbons, to form Acetyl CoA – 2 carbons • CO2 is lost in this process and NAD is reduced to NADH and H+.

8. Step 1 • The 2-carbon Acetyl CoA combines with a 4-carbon compound, Oxaloaceticacid, to form a 6-carbon molecule, Citric acid • This step regenerates Co-enzyme A so it can return back to join with pyruvic acid.

9. PREPARATORYSTEPS pyruvate coenzyme A (CoA) NAD+ (CO2) NADH CoA Acetyl–CoA KREBS CYCLE CoA oxaloacetate citrate H2O NADH H2O NAD+ isocitrate malate NAD+ H2O NADH fumarate a-ketogluterate FADH2 CoA NAD+ FAD NADH succinate CoA succinyl–CoA Fig. 7.6, p. 115 ADP + phosphate group (from GTP) ATP

10. Step 2 • Citric acid releases a CO2 and a hydrogen to form a 5-carbon compound • NAD+(electron acceptor) accepts an H+ to become NADH and H+.

11. Step 3 • The 5-carbon compound releases CO2 and H+ to form a 4-carbon compound. • NAD+ is reduced again to NADH and One molecules of ATP is made

12. Step 4 • The 4-carbon compound releases hydrogen • The hydrogen forms with FAD+ to form FADH2. FAD is another electron acceptor.

13. Step 5 • The 4-carbon compound releases a hydrogen to REFORMoxaloacetic acid • NAD+ is reduced again to NADH and H+

14. Summary of the Krebs Cycle • Glycolysis, produces 2 NADH and 2 pyruvic acid, 2 ATP. • One molecule of glucose from glycolysis needs 2 turns of the Krebs to produce: • Summary: 10 NADH, 2 FADH, 4 ATP, 4 CO2. The 10 NADH and 2 FADH (both energy molecules) will drive the next stage of cellular respiration in the Electron Transport Chain.

15. Krebs Cycle conclusion • Location – Mitochondrial Matrix (space inside the inner membrane) • Function – Produce Citric Acid and CO2. • Reactants – Pyruvic Acid, Acetlyl-CoA, Oxaloacitic Acid, NAD, FAD, ADP and C0enzyme A. • Products – CO2 NADH, FADH, ATP and Citric acid.

16. Compounds and their # of carbon atoms • CO2 – 1 Oxaloactic Acid - 4 • RuBP – 5 Citric Acid - 6 • PGA – 3 Co-enzyme A - 0 • PGAL – 3 • Glucose – 6 • Pyruvic Acid – 3 • Lactic Acid – 3 • Ethyl Alcohol – 2 • Acetyl – CoA - 2

17. The Electron Transport Chain in Cellular Respiration

18. Cellular Respiration • The process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.

19. Electron Transport Chain • A chemical reaction that uses high energy electrons made in the Krebs cycle to convert ADP into ATP. • Aerobic – means with oxygen • Anaerobic – means without oxygen

20. Location of the Electron Transport Chain • This occurs along the lining of the inner membranes of the mitochondria.

21. Made in the Krebs Cycle • NADH – Energy molecule made in the Krebs cycle and will be used in the ETC. • FADH – Energy molecule made in the Krebs cycle and will be used in the ETC. • FAD+ – Electron acceptor in the Krebs Cycle.

24. Steps of ETC • 1. Electrons from the hydrogens atoms of NADH and FADH are passed along a series of molecules, releasing energy along the way.

25. 2. This released energy creates a concentration gradient across the inner mitochondria membrane.

26. OUTER COMPARTMENT NADH INNER COMPARTMENT Fig. 7.7a, p. 116

27. 3. This high concentration gradient is what drives chemiosmosis ( ATP production) • ATP synthase is located in the inner membrane. ATP is made as protons move down their concentration gradient in the mitochondria.

28. Oxygen’s Role • Oxygen is the final electron acceptor, accepting electrons from the last molecule in the ETC. • This allows ATP to continue to be synthesized. • Oxygen also accepts the hydrogen atoms from NADH and FADH. • This combination of electron, hydrogens and oxygen forms WATER!!!!! O2 + e- +H- = H2O • Water – is made at the end of the ETC.

29. ATP NADH INNER COMPARTMENT ADP+Pi Fig. 7.7b, p. 116

30. Energy Yield • Per molecule of glucose, A total 36 ATP’s are produced. (Cellular/Aerobic Respiration) • Glycolysis – 2 ATP • Krebs – 2 ATP • ETC – 32 ATP

31. Krebs Cycle and ETC. • Both the Krebs Cycle and the Electron Transport chain cannot proceed without the presence of • O2 • H2O • CO2

32. Order of processes in Cellular Respiration. • 1. Glycolysis • 2. Krebs cycle • 3. Electron Transport Chain

33. Conclusion of Electron Transport Chain • Location – Lining of the inner membrane of the mitochondria. • Function – Produce ATP and water • Reactants – NADH, FADH, ADP and O2. • Products – NAD, FAD, ATP and Water

34. # of carbon atoms in compounds • CO2 – 1 PGA - 3 • RuBP – 5 PGAL - 3 • Glucose – 6 • Oxaloacitic Acid – 4 • Acetyl Co-A – 2 • Pyruvic Acid – 3 • Citric Acid – 6 • Lactic Acid – 3 • Ethyl Alcohol – 2 • Co-enzyme A - 0