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Glycolysis Review

Glycolysis Review. Acetyl-coA. oxaloacetate. Pyruvate (C3) (actually 2 of these go through cycle). citrate. Kreb’s Review. Citrate. NAD+. CO 2. ATP. Citrate. NADH. CO 2. oxaloacetate. Acetyl -CoA. Citrate (C6). H 2 O. Isomer change. H 2 O. Oxaloacetate (C4).

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Glycolysis Review

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  1. Glycolysis Review

  2. Acetyl-coA oxaloacetate Pyruvate (C3) (actually 2 of these go through cycle) citrate Kreb’s Review Citrate NAD+ CO2 ATP Citrate NADH CO2 oxaloacetate Acetyl -CoA Citrate (C6) H2O Isomer change H2O Oxaloacetate (C4) Isocitrate (C6) NADH CO2 NAD+ Decarboxylation NAD+ NADH Malate (C4) Ketoglutarate (C5) CO2 H2O Decarboxylation NAD+ Fumarate (C4) NADH Succinyl-CoA (C4) Pi *bumps off coA and briefly attaches to succinate,then to GDP FADH2 FAD Succinate(C4) GTP GDP ADP Substrate-level phosphorylation of ADP ATP

  3. ADP + Pi Chemiosmosis(oxidative phosphorylation) Proton pump (F1 Knob) ATP NADH NADH from Krebs ox red Each NADH from Krebs produces 3 ATPs through chemiosmosis H+ H+ NAD+ FADH2 red NADH from glycolysis and FADH2 from Krebs red ox Each NADH from glycolysis and each FADH2 produces 2 ATPs through chemiosmosis FAD+ ox H+ ox red H+ Proton pool red ox ox red H+ H+ Oxygen H2O

  4. Aerobic Respiration 1:08

  5. Theoretical vs. Actual Yield of ATP • The theoretical efficiency of aerobic respiration is 36 ATP • (36 ATP X 31 KJ per ATP / 2870 KJ per glucose) = 39% efficient • But the actual yield isn’t 36. This is due to: • Some leaking of H+ through the inner mito membrane, reducing the number going through the pump to make ATP • Some protons are used for other energy-requiring activities • The more realistic estimate is • 2.5 (not 3) ATP produced per NADH • 1.5 (not 2) ATP procuced per FADH2 • So: glycolysis – 2 ATP, 2 NADH X 1.5 ATP • Kreb’s – 2 ATP, 8 NADH X 2.5 ATP, 2 FADH2 X 1.5 ATP • Realistic total is 30 ATP (32 % efficient) • *Always use theoretical numbers unless told to use realistic yield

  6. Section 2.3: Related Pathways • Carbohydrates are the first nutrients most organisms catabolize for energy. However, when necessary, most organisms can metabolize proteins, lipids and nucleic acids.

  7. Carbohydrate Catabolism • Starches/Sugars - all convert to glucose and enter at the beginning of glycolysis • count the number of monosaccharides: • eg. sucrose = fructose + glucose = 72 ATP

  8. See M6 pkg

  9. Starch/Sugar See M6 pkg

  10. Protein Catabolism • hydrolysed into a.a.s • then deaminated so only C’s are left • enter Kreb’s at various points • Amino acid conversion to Kreb’s intermediates can be complicated so we will simplify and assume they enter at a point based on the number of carbons • Alanine  3 carbons, becomes pyruvate • Proline  5 carbons, becomes α ketoglutarate

  11. Proteins Starch/Sugar See M6 pkg hydrolysis ammonia aa’s deamination remaining # carbons 3C 2C 6C 5C 4C

  12. Lipid Catabolism • Triglycerides  glycerol + fatty acids • Glycerol  Glucose (gluconeogenesis) or DHAP then G3P. • If glycerol - enters at G3P glycolysis 2 ATP • 1NADH (x2 ATP) = 2 ATP • Krebs 1 ATP • 4 NADH (x3 ATP) = 12 ATP • 1 FADH2 (x2 ATP) = 2 ATP Total = 19 ATP from glycerol (theoretically)

  13. Lipid Catabolism • Fatty acids  β-oxidation (matrix) - cleaved into 2 carbon bits that enter at acetyl coA • each cleave - requires 1 ATP • - makes 1NADH (x3 ATP) = 3 ATP • - makes 1FADH2 (x2 ATP) = 2 ATP • = net of 4 ATP per cleave • each bit - enters at acetyl coA so how many ATP per bit? Follow along on M5/next slide

  14. Acetyl-coA oxaloacetate Pyruvate (C3) (actually 2 of these go through cycle) citrate Kreb’s Review Citrate NAD+ CO2 ATP Citrate NADH CO2 oxaloacetate Acetyl -CoA Citrate (C6) H2O Isomer change H2O Oxaloacetate (C4) Isocitrate (C6) NADH CO2 NAD+ Decarboxylation NAD+ NADH Malate (C4) Ketoglutarate (C5) CO2 H2O Decarboxylation NAD+ Fumarate (C4) NADH Succinyl-CoA (C4) Pi *bumps off coA and briefly attaches to succinate,then to GDP FADH2 FAD Succinate(C4) GTP GDP ADP Substrate-level phosphorylation of ADP ATP

  15. Lipid Catabolism • Fatty acids  β-oxidation (matrix) - cleaved into 2 carbon bits that enter at acetyl coA • each cleave - requires 1 ATP • - makes 1NADH (x3 ATP) = 3 ATP • - makes 1FADH2 (x2 ATP) = 2 ATP • = net of 4 ATP per cleave • each bit - enters at acetyl coA so how many ATP per bit? • Each Acetyl coA produces 1 ATP • 3 NADH (x3 ATP) = 9 ATP • 1 FADH2 (x2 ATP) = 2 ATP • = 12 ATP per bit However each fatty acid requires 2 ATP to activate. So you must subtract 2 ATP for each fatty acid (if it is a triglyceride, there are 3 fatty acids) • Produces more ATP than Glucose Weblink: Fatty Acid Metabolism- Interactive Animations

  16. Proteins Fats Starch/Sugar See M6 pkg hydrolysis ammonia hydrolysis aa’s gluconeogenesis deamination Fatty acids / Glycerol remaining # carbons 3C 2C 6C 5C 4C

  17. Proteins Fats Starch/Sugar See M6 pkg hydrolysis ammonia hydrolysis aa’s gluconeogenesis deamination Fatty acids / Glycerol remaining # carbons  oxidation 3C 2C 6C 5C 4C

  18. Question Example • - calculate the energy from a triglyceride n= 6, 8, 4 • Glycerol glycerol 19 ATP • f.a. #1 n=6 2 cleaves (x4), 3 bits (x12) chain #1 44 ATP • f.a. #2 n=8 3 cleaves (x4), 4 bits (x12) chain #2 60 ATP • f.a. #3 n=4 1 cleave (x4), 2 bits (x2) chain #3 28 ATP • so far 151 ATP • But each fa requires 2 ATP to activate - 6 ATP • Total 145 ATP

  19. b Oxidation Overview

  20. Homework: • M6 pkg Q’s on bottom • M7 and M8 duotang • read tomorrow’s lab M9-M10 and make hypothesis, copy out data table The following slides provide more details than are necessary for SBI 4UO but are included for complete explanation

  21. Definitions • b Oxidation – fatty acids are used to make Acyl-CoA molecules and broken down in mitochondria to make Acetyl-CoA molecules, which can enter the Krebs Cycle. • Acyl-CoA – temporary compound formed when coenzyme attaches to fatty acid. • It is the long fatty acid plus coA. • 2-Carbon bits are cleaved off, so it becomes shorter and shorter as the process procedes.

  22. Step 1: Activation of Fatty Acids by Acetyl CoA Note: 2P from ATP are utilized in this process

  23. Step 2: AcylCoA Enters the Matrix

  24. Step 3: Oxidation of AcylCoA 1. FAD+ oxidizes the bond between C2 and C3 2. Adding water results in the addition of OH to C3 3. NAD+ oxidizes that OH to a carbonyl group 4. CoA cleaves the bond between C2 and C3

  25. Notes • C1 = alpha C (Ca) and C2 = beta C (Cb), hence the term beta oxidation • Products: • Shorter AcylCoA (which continues to undergo b oxidation again and again until all 2C bits are cleaved) • Acetyl CoA (which enters the Krebs cycle) • NADH and FADH2 (which are utilized by ETC)

  26. Details • Each cleave: • requires 1 ATP • makes 1 NADH (X3 ATP) = 3 ATP • makes 1 FADH2 (X2 ATP) = 2 ATP = net of 4 ATP per cleave • Each Bit enters at Acetyl coA: • makes 1 ATP • makes 3 NADH (X3 ATP) = 9 ATP • Makes 1 FADH2 (X2 ATP) = 2 ATP = net of 12 ATP per bit

  27. Example: Palmitate (16 C) ATP Yield Palmitoyl CoA + 7FAD + 7NAD + 7CoA + 7H2O + 7 ATP for cleaves 8Acetyl CoA bits + 7FADH2 + 7NADH + 7H+ from the cleaves

  28. How much ATP did Palmitate yield? • 8 acetyl CoA enter citric acid cycle and give: • 24 NADH = 72 ATP (by oxidative phosphorylation) • 8 FADH2 = 16 ATP (by oxidative phosphorylation) (8 bits X 12 ATP = 96) • 8 GTP = 8 ATP • 7 NADH generated by beta oxidation itself = 21 ATP (by oxidative phosphorylation) • 7 FADH2 generated by beta oxidation itself =14 ATP (by oxidative phosphorylation) • 7 ATP required for the cleaves = - 7 ATP(7 cleaves X 4 ATP = 28) • Total ATP from 1 molecule of palmitate = 72 + 16 + 8 + 21 + 14 - 7 = 124. • But REMEMBER: we used to high energy phosphate bonds (equivalent of 2 ATP) to activate palmitate to palmitoyl CoA. Therefore, the ATP yield is 122.

  29. Let’s compare 12-C from 2 glucose to 12-C from one laurate fatty acid… Fats generate much more ATP and energy than Carbohydrates!

  30. Anaerobic Respiration • During oxygen deficient periods, the process of cellular respiration can get backed up. • NADH cannot get recycled back to NAD+ to pick up more electrons. • Organisms have evolved a way to recycle NAD+ and allow glycolysis to continue.

  31. Fermentation: ATP from Glucose, without O2 • Many organisms and some cells live without O2, deriving energy from glycolysis and fermentation. Together, these pathways partly oxidize glucose and generate energy-containing products. Fermentation reactions anaerobically oxidize the NADH + H+ produced in glycolysis.

  32. Anaerobic Pathways • Required to recycle NADH when oxygen levels are low. • Ethanol Fermentation • NADH passes it H atoms to acetaldehyde (formed when CO2 is removed from pyruvate), this forms ethanol. • NAD+ can be recycled and glycolysis continues. • Lactic Acid Fermenatation • NADH transfers its H atoms to pyruvate forming lactate

  33. Figure 7.15 Lactic Acid Fermentation

  34. Lactic Acid Fermentation • NADH transfers its hydrogen atoms to pyruvate to form lactate • Lactate can be oxidized back to pyruvate when the strenuous exercise stops • Extra oxygen (oxygen debt) is required to catabolize lactate into CO2 and H2O

  35. Figure 7.16 Alcoholic Fermentation

  36. Ethanol Fermentation • CO2 is removed from pyruvate to form acetaldehyde • NADH passes its hydrogen atoms to acetaldehyde to form ethanol • Carried out by yeast • Breads, wine, beer, liquor, soy sauce

  37. Contrasting Energy Yields • For each molecule of glucose used, fermentation yields 2 molecules of ATP. In contrast, glycolysis operating with pyruvate oxidation, the citric acid cycle, and the respiratory chain yields up to 36.

  38. Figure 7.17 – Part 1 Energy Yields

  39. Figure 7.17 – Part 2 Energy Yields

  40. Metabolic Pathways - Metabolic Mill • Catabolic pathways feed into the respiratory pathways. Polysaccharides are broken down into glucose, which enters glycolysis. Glycerol from fats also enters glycolysis, and acetyl CoA from fatty acid degradation enters the citric acid cycle. Proteins enter glycolysis and the citric acid cycle via amino acids. • Anabolic pathways use intermediate components of respiratory metabolism to synthesize fats, amino acids, and other essential building blocks for cellular structure and function.

  41. Figure 7.18 The Metabolic Mill

  42. VO2 Max and Lactate Threshold Aerobic fitness • the ability of the heart, lungs, and bloodstream to supply oxygen to the cells of the body during physical activity. VO2 max: • The max.volume of oxygen (mL) that the cells of the body can remove from the bloodstream in one minute/kg of body mass while the body experiences maximal exertion • Typical value: 35 mL/kg/min • Elite athletes: 70 mL/kg/min

  43. Videos\VO2 Max Test.flv

  44. Lactate Threshold

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