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Molbiol 2011-04-metabolism


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Molbiol 2011-04-metabolism

  1. 1. ЛЕКЦИЯ 3-2 <ul><li>Метаболизм </li></ul>
  2. 2. <ul><li>Metabolism: The sum of the chemical reactions in an organism </li></ul><ul><li>Catabolism: The energy-releasing processes </li></ul><ul><li>Anabolism: The energy-using processes </li></ul>Microbial Metabolism
  3. 3. Microbial Metabolism <ul><li>Catabolism provides the building blocks and energy for anabolism. </li></ul>Figure 5.1
  4. 4. <ul><li>A metabolic pathway is a sequence of enzymatically catalyzed chemical reactions in a cell. </li></ul><ul><li>Metabolic pathways are determined by enzymes. </li></ul><ul><li>Enzymes are encoded by genes. </li></ul>PLAY Animation: Metabolic Pathways (Overview)
  5. 5. <ul><li>The collision theory states that chemical reactions can occur when atoms, ions, and molecules collide. </li></ul><ul><li>Activation energy is needed to disrupt electronic configurations. </li></ul><ul><li>Reaction rate is the frequency of collisions with enough energy to bring about a reaction. </li></ul><ul><li>Reaction rate can be increased by enzymes or by increasing temperature or pressure. </li></ul>
  6. 6. Enzymes Figure 5.2
  7. 7. Enzymes <ul><li>Biological catalysts </li></ul><ul><ul><li>Specific for a chemical reaction; not used up in that reaction </li></ul></ul><ul><li>Apoenzyme: Protein </li></ul><ul><li>Cofactor: Nonprotein component </li></ul><ul><ul><li>Coenzyme: Organic cofactor </li></ul></ul><ul><li>Holoenzyme: Apoenzyme plus cofactor </li></ul>
  8. 8. Enzymes Figure 5.3
  9. 9. Important Coenzymes <ul><li>NAD + </li></ul><ul><li>NADP + </li></ul><ul><li>FAD </li></ul><ul><li>Coenzyme A </li></ul>
  10. 10. Enzymes <ul><li>The turnover number is generally 1-10,000 molecules per second. </li></ul>PLAY Animation: Enzyme–Substrate Interactions Figure 5.4
  11. 11. Enzyme Classification <ul><li>Oxidoreductase: Oxidation-reduction reactions </li></ul><ul><li>Transferase: Transfer functional groups </li></ul><ul><li>Hydrolase: Hydrolysis </li></ul><ul><li>Lyase: Removal of atoms without hydrolysis </li></ul><ul><li>Isomerase: Rearrangement of atoms </li></ul><ul><li>Ligase: Joining of molecules, uses ATP </li></ul>
  12. 12. Factors Influencing Enzyme Activity <ul><li>Enzymes can be denatured by temperature and pH </li></ul>Figure 5.6
  13. 13. Factors Influencing Enzyme Activity <ul><li>Temperature </li></ul>Figure 5.5a
  14. 14. Factors Influencing Enzyme Activity <ul><li>pH </li></ul>Figure 5.5b
  15. 15. Factors Influencing Enzyme Activity <ul><li>Substrate concentration </li></ul>Figure 5.5c
  16. 16. Factors Influencing Enzyme Activity <ul><li>Competitive inhibition </li></ul>Figure 5.7a–b
  17. 17. Factors Influencing Enzyme Activity
  18. 18. Factors Influencing Enzyme Activity <ul><li>Noncompetitive inhibition </li></ul>Figure 5.7a, c
  19. 19. Factors Influencing Enzyme Activity <ul><li>Feedback inhibition </li></ul>Figure 5.8
  20. 20. Ribozymes <ul><li>RNA that cuts and splices RNA </li></ul>
  21. 21. Oxidation-Reduction <ul><li>Oxidation is the removal of electrons. </li></ul><ul><li>Reduction is the gain of electrons. </li></ul><ul><li>Redox reaction is an oxidation reaction paired with a reduction reaction. </li></ul>Figure 5.9
  22. 22. Oxidation-Reduction <ul><li>In biological systems, the electrons are often associated with hydrogen atoms. Biological oxidations are often dehydrogenations. </li></ul>Figure 5.10
  23. 23. The Generation of ATP <ul><li>ATP is generated by the phosphorylation of ADP. </li></ul>
  24. 24. The Generation of ATP <ul><li>Substrate-level phosphorylation is the transfer of a high-energy PO 4 – to ADP. </li></ul>
  25. 25. The Generation of ATP <ul><li>Energy released from the transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP by chemiosmosis. </li></ul>
  26. 26. The Generation of ATP <ul><li>Light causes chlorophyll to give up electrons. Energy released from the transfer of electrons (oxidation) of chlorophyll through a system of carrier molecules is used to generate ATP. </li></ul>
  27. 27. Metabolic Pathways
  28. 28. Carbohydrate Catabolism <ul><li>The breakdown of carbohydrates to release energy </li></ul><ul><ul><li>Glycolysis </li></ul></ul><ul><ul><li>Krebs cycle </li></ul></ul><ul><ul><li>Electron transport chain </li></ul></ul>
  29. 29. Glycolysis <ul><li>The oxidation of glucose to pyruvic acid produces ATP and NADH. </li></ul>Figure 5.11, step 1
  30. 30. Preparatory Stage <ul><li>Two ATPs are used </li></ul><ul><li>Glucose is split to form two Glucose-3-phosphate </li></ul>1 3 4 5 Figure 5.12, step 1
  31. 31. Energy-Conserving Stage <ul><li>Two Glucose-3-phosphate oxidized to two Pyruvic acid </li></ul><ul><li>Four ATP produced </li></ul><ul><li>Two NADH produced </li></ul>9 Figure 5.12, step 2
  32. 32. Glycolysis <ul><li>Glucose + 2 ATP + 2 ADP + 2 PO 4 – + 2 NAD +  2 pyruvic acid + 4 ATP + 2 NADH + 2H + </li></ul>PLAY Animation: Glycolysis
  33. 33. Alternatives to Glycolysis <ul><li>Pentose phosphate pathway </li></ul><ul><ul><li>Uses pentoses and NADPH </li></ul></ul><ul><ul><li>Operates with glycolysis </li></ul></ul><ul><li>Entner-Doudoroff pathway </li></ul><ul><ul><li>Produces NADPH and ATP </li></ul></ul><ul><ul><li>Does not involve glycolysis </li></ul></ul><ul><ul><li>Pseudomonas, Rhizobium, Agrobacterium </li></ul></ul>
  34. 34. Cellular Respiration <ul><li>Oxidation of molecules liberates electrons for an electron transport chain. </li></ul><ul><li>ATP is generated by oxidative phosphorylation. </li></ul>
  35. 35. Intermediate Step <ul><li>Pyruvic acid (from glycolysis) is oxidized and decarboyxlated. </li></ul>Figure 5.13 (1 of 2)
  36. 36. Krebs Cycle <ul><li>Oxidation of acetyl CoA produces NADH and FADH 2 . </li></ul>PLAY Animation: Krebs Cycle
  37. 37. Krebs Cycle Figure 5.13 (2 of 2)
  38. 38. The Electron Transport Chain <ul><li>A series of carrier molecules that are, in turn, oxidized and reduced as electrons are passed down the chain. </li></ul><ul><li>Energy released can be used to produce ATP by chemiosmosis. </li></ul>PLAY Animation: Electron Transport Chains and Chemiosmosis
  39. 39. Figure 5.11
  40. 40. Chemiosmosis Figure 5.16
  41. 41. Chemiosmosis Figure 5.15
  42. 42. Respiration <ul><li>Aerobic respiration: The final electron acceptor in the electron transport chain is molecular oxygen (O 2 ). </li></ul><ul><li>Anaerobic respiration: The final electron acceptor in the electron transport chain is not O 2 . Yields less energy than aerobic respiration because only part of the Krebs cycles operations under anaerobic conditions. </li></ul>
  43. 43. Anaerobic Respiration CH 4 + H 2 O CO 3 2 – H 2 S + H 2 O SO 4 – NO 2 – , N 2 + H 2 O NO 3 – Products Electron acceptor
  44. 44. Plasma membrane Mitochondrial inner membrane ETC Cytoplasm Cytoplasm Cytoplasm Prokaryote Mitochondrial matrix Krebs cycle Cytoplasm Intermediate step Cytoplasm Glycolysis Eukaryote Pathway
  45. 45. <ul><li>Energy produced from complete oxidation of one glucose using aerobic respiration. </li></ul>2 2 0 FADH 2 produced 10 4 Total 6 2 2 NADH produced 2 Krebs cycle 0 Intermediate step 2 Glycolysis ATP produced Pathway
  46. 46. <ul><li>ATP produced from complete oxidation of one glucose using aerobic respiration. </li></ul><ul><li>36 ATPs are produced in eukaryotes. </li></ul>4 30 4 Total 4 0 From FADH 18 2 Krebs cycle 6 6 From NADH By oxidative phosphorylation 0 Intermediate step 2 Glycolysis By substrate-level phosphorylation Pathway