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BCM311 - Carbohydrate Metabolism

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BCM311 - Carbohydrate Metabolism

  1. 1. - Also known as Respiration. - Comprises of these different processes depending on type of organism: I. Anaerobic Respiration II. Aerobic Respiration
  2. 2. Comprises of these stages: glycolysis: glucose 2 pyruvate + NADH fermentation: pyruvate lactic acid or ethanol cellular respiration:
  3. 3. Comprises of these stages: Oxidative decarboxylation of pyruvate Citric Acid cycle Oxidative phosphorylation/ Electron Transport Chain(ETC)
  4. 4. Brief overview of STARCHYcatabolism of FOODglucose to generate α – AMYLASE ; MALTASESenergy Glucose Glucose converted to glu-6-PO4 Start of cycle Glycolysis inCycle : anaerobic cytosol Aerobic condition; 2[Pyruvate+ATP+NADH] in mitochondria Anaerobic condition Pyruvate enters as AcetylcoA - Krebs Cycle Lactic Acid fermentation in muscle. - E transport chain Only in yeast/bacteria Anaerobic respiration or Alcohol fermentation
  5. 5. Show time..
  6. 6.  1st stage of glucose metabolism → glycolysis An anaerobic process, yields 2 ATP (additional energy source) Glucose will be metabolized via gycolysis; pyruvate as the end product The pyruvate will be converted to lactic acid (muscles → liver) Aerobic conditions: the main purpose is to feed pyruvate into TCA cycle for further rise of ATP
  7. 7. The breakdown of glucose to pyruvate as summarized:Glucose (six C atoms) → 2 pyruvate (three C atoms)2 ATP + 4 ADP + 2 Pi → 2 ADP + 4 ATP (phosphorylation)Glucose + 2 ADP + 2 Pi → 2 Pyruvate + 2 ATP (Net reaction) Fig. 17-1, p.464
  8. 8. Fig. 17-2, p.465
  9. 9. Louis Pasteur- French biologist- did research onfermentationwhich led toimportantdiscoveries inmicrobiology andchemistry
  10. 10. Preparation phaseStep 1 Glucose is phosphorylated to give gluc-6-phosphate p.467
  11. 11. Fig. 17-3, p.468
  12. 12. Table 17-1, p.469
  13. 13. Fig. 17-4, p.470
  14. 14. Step 2 Glucose-6-phosphate isomerize to give fructose-6- phosphate p.470a
  15. 15. Step 3 Fructose-6-phosphate is phosphorylated producing fructose-1,6-bisphosphate p.470b
  16. 16. Fig. 17-6, p.471
  17. 17. Step 4 Fructose-1,6-bisphosphate split into two 3-carbon fragments p.471a
  18. 18. Step 5 Dihydroxyacetone phosphate is converted to glyceraldehyde-3-phosphate p.471b
  19. 19. Payoff phaseStep 6 Glyceraldehyde-6-phosphate is oxidized to 1,3-bisphosphoglycerate p.472
  20. 20. Fig. 17-7, p.473
  21. 21. p.474a
  22. 22. Fig. 17-8, p.475
  23. 23. Step 7 Production of ATP by phosphorylation of ADP p.476
  24. 24. Step 8 Phosphate group is transferred from C-3 to C-2 p.477a
  25. 25. Step 9 Dehydration reaction of 2-phosphoglycerate to phosphoenolpyruvate p.477b
  26. 26. Step 10 Phosphoenolpyruvate transfers its phosphate group to ADP → ATP and pyruvate p.478
  27. 27. Control points inglycolysis Fig. 17-10, p.479
  28. 28. Conversion of pyruvate to lactate in muscle p.479
  29. 29. Fig. 17-11b, p.481
  30. 30. Pyruvatedecarboxylase Fig. 17-11a, p.481
  31. 31. Fig. 17-12, p.482
  32. 32. Acetaldehyde + NADH → Ethanol + NAD+Glucose + 2 ADP + 2 Pi + 2 H+ → 2 Ethanol + 2 ATP + 2 CO2 + 2 H2O p.482
  33. 33. Carbohydrate metabolism
  34. 34. Gluconeogenesis Conversion of pyruvate to glucose Biosynthesis and the degradation of many important biomolecules follow different pathways There are three irreversible steps in glycolysis and the differences bet. glycolysis and gluconeogenesis are found in these reactions Different pathway, reactions and enzymeST E P1 p.495
  35. 35.  is the biosynthesis of new glucose from non-CHO precursors. this glucose is as a fuel source by the brain, testes, erythrocytes and kidney medulla comprises of 9 steps and occurs in liver and kidney the process occurs when quantity of glycogen have been depleted - Used to maintain blood glucose levels. Designed to make sure blood glucose levels are high enough to meet the demands of brain and muscle (cannot do gluconeogenesis). promotes by low blood glucose level and high ATP inhibits by low ATP occurs when [glu] is low or during periods of fasting/starvation, or intense exercise pathway is highly endergonic *endergonic is energy consuming
  36. 36. STEP 2
  37. 37.  The oxalocetate formed in the mitochondria have two fates: - continue to form PEP - turned into malate by malate dehydrogenase and leave the mitochondria, have a reaction reverse by cytosolic malate dehydrogenase Reason?
  38. 38. Controlling glucosemetabolism• found in Cori cycle• shows the cycling ofglucose due togycolysis in muscle andgluconeogenesis inliver • This two metabolic pathways are not active simultaneously. As energy store for • when the cell needs next exercise ATP, glycolisys is more active •When there is little need for ATP, gluconeogenesis is more active Fig. 18-12, p.502
  39. 39. Cori cycle requires the net hydrolysis of two ATP and two GTP. glu cos e + 2 NAD + + 2 ADP + 2 Pi → + 2 Pyruvate + 2 NADH + 4 H + 2 ATP + 2 H 2O +2 Pyruvate + 2 NADH + 4 H + 4 ATP + 2GTP + 6 H 2O →Glu cos e + 2 NAD + + 4 ADP + 2GDP + 6 Pi 2 ATP + 2GTP + 4 H 2O → 2 ADP + 2GDP + 4 Pi
  40. 40. Fig. 18-13, p.503
  41. 41. The Citric Acid cycle Cycle where 30 to 32 molecules of ATP can be produced from glucose in complete aerobic oxidation Amphibolic – play roles in both catabolism and anabolism The other name of citric acid cycle: Krebs cycle and tricarboxylic acid cycle (TCA) Takes place in mitochondria
  42. 42. Fig. 19-2, p.513
  43. 43. Steps 3,4,6 and 8 –oxidation reactions Fig. 19-3b, p.514
  44. 44. 5 enzymes make up the pyruvate dehydrogenase complex:  pyruvate dehydrogenase (PDH) Conversion of pyruvate  Dihydrolipoyl transacetylase to acetyl-CoA  Dihydrolipoyl dehydrogenase  Pyruvate dehydrogenase kinase  Pyruvate dehydrogenase phosphatase
  45. 45. Step 1 Formation of citrate p.518
  46. 46. Step 2 Isomerization Table 19-1, p.518
  47. 47. cis-Aconitate as an intermediate inthe conversion of citrate to isocitrate Fig. 19-6, p.519
  48. 48. Step 3Formation of α-ketoglutarateand CO2 – firstoxidation Fig. 19-7, p.521
  49. 49. Step 4 Formation of succinyl-CoA and CO2 – 2nd oxidation p.521
  50. 50. Step 5 Formation of succinate p.522
  51. 51. Step 6Formation offumarate –FAD-linkedoxidation p.523a
  52. 52. Step 7 Formation of L-malate p.524a
  53. 53. Step 8 Regeneration of oxaloacetate – final oxidation step p.524b
  54. 54. Krebs cycle produced:• 6 CO2• 2 ATP• 6 NADH• 2 FADH2 Fig. 19-8, p.526
  55. 55. Table 19-3, p.527
  56. 56. Fig. 19-10, p.530
  57. 57. Fig. 19-11, p.531
  58. 58. Fig. 19-12, p.533
  59. 59. Fig. 19-15, p.535
  60. 60. Overall production from glycolysis, oxidativedecarboxylation and TCA: Oxidative Glycolysis TCA cycle decarboxylation - 2 ATP 2 ATP 2 NADH 2 NADH 6 NADH , 2 FADH2 2 CO2 2 Pyruvate 4 CO2 Electron transportation system

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