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  1. 1. Cell Respiration and Metabolism www.freelivedoctor.com
  2. 2. Metabolism <ul><li>All reactions that involve energy transformations. </li></ul><ul><li>Divided into 2 Categories: </li></ul><ul><ul><li>Catabolic: </li></ul></ul><ul><ul><ul><li>Release energy. </li></ul></ul></ul><ul><ul><ul><li>Breakdown larger molecules into smaller molecules. </li></ul></ul></ul><ul><ul><li>Anabolic: </li></ul></ul><ul><ul><ul><li>Require input of energy. </li></ul></ul></ul><ul><ul><ul><li>Synthesis of large energy-storage molecules. </li></ul></ul></ul>www.freelivedoctor.com
  3. 3. Aerobic Cell Respiration <ul><li>Oxidation-reduction reactions: </li></ul><ul><ul><li>Break down of molecules for energy. </li></ul></ul><ul><ul><li>Electrons are transferred to intermediate carriers, then to the final electron acceptor: oxygen. </li></ul></ul><ul><ul><ul><li>Oxygen is obtained from the blood. </li></ul></ul></ul>www.freelivedoctor.com
  4. 4. Glycolysis <ul><li>Breakdown of glucose for energy in the cytoplasm. </li></ul><ul><li>Glucose is converted to 2 molecules of pyruvic acid (pyruvate). </li></ul><ul><li>Each pyruvic acid contains: </li></ul><ul><ul><li>3 carbons </li></ul></ul><ul><ul><li>3 oxygens </li></ul></ul><ul><ul><li>4 hydrogens </li></ul></ul><ul><li>4 hydrogens are removed from intermediates. </li></ul>www.freelivedoctor.com
  5. 5. www.freelivedoctor.com
  6. 6. Glycolysis <ul><li>Each pair of H + reduces a molecule of NAD. </li></ul><ul><li>Produces: </li></ul><ul><ul><li>2 molecules of NADH and 2 unbound H + </li></ul></ul><ul><ul><li>2 ATP </li></ul></ul><ul><li>Glycolysis Pathway: </li></ul><ul><li>Glucose + 2 NAD + 2 ADP + 2 P i </li></ul><ul><li>2 pyruvic acid + 2 NADH and 2 ATP </li></ul>www.freelivedoctor.com
  7. 7. Glycolysis <ul><li>Glycolysis is exergonic. </li></ul><ul><ul><li>Energy released used to drive endergonic reaction: </li></ul></ul><ul><ul><ul><li>ADP + P i ATP </li></ul></ul></ul><ul><li>Glucose must be activated first before energy can be obtained. </li></ul><ul><ul><li>ATP consumed at the beginning of glycolysis. </li></ul></ul>www.freelivedoctor.com
  8. 8. Glycolysis <ul><li>ATP ADP + P i </li></ul><ul><li>P i is not released but added to intermediate molecules (phosphorylation). </li></ul><ul><li>Phosphorylation of glucose, traps the glucose inside the cell. </li></ul><ul><li>Net gain of 2 ATP and 2 NADH. </li></ul>www.freelivedoctor.com
  9. 9. www.freelivedoctor.com
  10. 10. Glycolysis www.freelivedoctor.com
  11. 11. Lactic Acid Pathway <ul><li>Anaerobic respiration: </li></ul><ul><ul><li>Oxygen is not used in the process. </li></ul></ul><ul><li>NADH + H + + pyruvic acid lactic acid and NAD. </li></ul><ul><li>Produce 2 ATP/ glucose molecule. </li></ul>www.freelivedoctor.com
  12. 12. Lactic Acid Pathway <ul><li>Some tissues adapted to anaerobic metabolism: </li></ul><ul><ul><li>Skeletal muscle: normal daily occurrence. </li></ul></ul><ul><ul><li>RBCs do not contain mitochondria and only use lactic acid pathway. </li></ul></ul><ul><li>Cardiac muscle: ischemia </li></ul>www.freelivedoctor.com
  13. 13. www.freelivedoctor.com
  14. 14. Glycogenesis and Glycogenolysis <ul><li>Increase glucose intracellularly, would increase osmotic pressure. </li></ul><ul><li>Must store carbohydrates in form of glycogen. </li></ul>www.freelivedoctor.com
  15. 15. <ul><li>Glycogenesis: formation of glycogen from glucose. </li></ul><ul><li>Glycogenolysis: conversion of glycogen to glucose-6-phosphate. </li></ul><ul><ul><li>Glucose-6-phosphate can be utilized through glycolysis. </li></ul></ul>www.freelivedoctor.com
  16. 16. Glycogenesis and Glycogenolysis <ul><li>Glucose-6-phosphate cannot leak out of the cell. </li></ul><ul><li>Skeletal muscles generate glucose-6-phosphate for own glycolytic needs. </li></ul><ul><li>Liver contains the enzyme glucose-6-phosphatase that can remove the phosphate group and produce free glucose. </li></ul>www.freelivedoctor.com
  17. 17. Cori Cycle <ul><li>Lactic acid produced by anaerobic respiration delivered to the liver. </li></ul><ul><li>LDH converts lactic acid to pyruvic acid. </li></ul><ul><li>Pyruvic acid converted to glucose-6-phosphate: </li></ul><ul><ul><li>Intermediate for glycogen. </li></ul></ul><ul><ul><li>Converted to free glucose. </li></ul></ul><ul><li>Gluconeogenesis: conversion to non-carbohydrate molecules through pyruvic acid to glucose. </li></ul>www.freelivedoctor.com
  18. 18. www.freelivedoctor.com
  19. 19. Aerobic Respiration <ul><li>Aerobic respiration of glucose, pyruvic acid is formed by glycolysis, then converted into acetyl coenzyme A (acetyl CoA). </li></ul><ul><li>Energy is released in oxidative reactions, and is captured as ATP. </li></ul>www.freelivedoctor.com
  20. 20. Aerobic Respiration <ul><li>Pyruvic acid enters interior of mitochondria. </li></ul><ul><li>Converted to acetyl CoA and 2 C0 2 . </li></ul><ul><li>Acetyl CoA serves as substrate for mitochondrial enzymes. </li></ul>www.freelivedoctor.com
  21. 21. Acetyl CoA enters the Krebs Cycle. www.freelivedoctor.com
  22. 22. overview www.freelivedoctor.com
  23. 23. Krebs Cycle <ul><li>Acetyl CoA combines with oxaloacetic acid to form citric acid. </li></ul><ul><li>Citric acid enters the Krebs Cycle. </li></ul><ul><li>Produces oxaloacetic acid to continue the pathway. </li></ul><ul><li>1 GTP, 3 NADH, and 1 FADH 2 </li></ul><ul><li>NADH and FADH 2 transport electrons to Electron Transport Cycle. </li></ul>www.freelivedoctor.com
  24. 24. CAC www.freelivedoctor.com
  25. 25. www.freelivedoctor.com
  26. 26. Electron Transport <ul><li>Cristae of inner mitochondrial membrane contain molecules that serve as electron transport system. </li></ul><ul><li>Electron transport chain consists of FMN, coenzyme Q, and cytochromes. </li></ul>www.freelivedoctor.com
  27. 27. ETC Chain <ul><li>Each cytochrome transfers electron pairs from NADH and FADH 2 to next cytochrome. </li></ul><ul><li>Oxidized NAD and FAD are regenerated and shuttle electrons from the Krebs Cycle to the ETC. </li></ul><ul><li>Cytochrome receives a pair of electrons. </li></ul><ul><li>Iron reduced, then oxidized as electrons are transferred. </li></ul>www.freelivedoctor.com
  28. 28. ETC Chain <ul><li>Cytochrome a 3 transfers electrons to O 2 (final electron acceptor). </li></ul><ul><li>Oxidative phosphorylation occurs: </li></ul><ul><ul><li>Energy derived is used to phosphorylate ADP to ATP. </li></ul></ul>www.freelivedoctor.com
  29. 29. www.freelivedoctor.com
  30. 30. Coupling ETC to ATP <ul><li>Chemiosmotic theory: </li></ul><ul><li>ETC powered by transport of electrons, pumps H + from mitochondria matrix into space between inner and outer mitochondrial membranes. </li></ul>www.freelivedoctor.com
  31. 31. Coupling ETC to ATP <ul><li>Proton pumps: </li></ul><ul><li>NADH-coenzyme Q reductase complex: </li></ul><ul><ul><li>Transports 4 H + for every pair of electrons. </li></ul></ul><ul><li>Cytochrome C reductase complex: </li></ul><ul><ul><li>Transports 4 H + . </li></ul></ul><ul><li>Cytochrome C oxidase complex: </li></ul><ul><ul><li>Transports 2 H + . </li></ul></ul>www.freelivedoctor.com
  32. 32. Coupling ETC to ATP <ul><li>Higher [H + ] in inter-membrane space. </li></ul><ul><li>Respiratory assemblies: </li></ul><ul><ul><li>Permit the passage of H + . </li></ul></ul><ul><li>Phosphorylation is coupled to oxidation, when H + diffuse through the respiratory assemblies: </li></ul><ul><ul><li>ADP and P i ATP </li></ul></ul>www.freelivedoctor.com
  33. 33. Coupling ETC to ATP <ul><li>Oxygen functions as the last electron acceptor. </li></ul><ul><ul><li>Oxidizes cytochrome a 3 . </li></ul></ul><ul><li>Oxygen accepts 2 electrons. </li></ul><ul><li>O 2 + 4 e - + 4 H + 2 H 2 0 </li></ul>www.freelivedoctor.com
  34. 34. www.freelivedoctor.com
  35. 35. ATP Produced <ul><li>Direct phosphorylation: </li></ul><ul><li>Glycolysis: </li></ul><ul><ul><li>2 ATP </li></ul></ul><ul><li>Oxidative phosphorylation: </li></ul><ul><ul><li>2.5 ATP produced for pair of electrons each NADH donates. </li></ul></ul><ul><ul><li>1.5 ATP produced for each pair of electrons FADH 2 donates ((activates 2 nd and 3 rd proton pumps). </li></ul></ul><ul><ul><li>26 ATP produced. </li></ul></ul>www.freelivedoctor.com
  36. 36. Metabolism of Lipids <ul><li>When more energy is taken in than consumed, glycolysis inhibited. </li></ul><ul><li>Glucose converted into glycogen and fat. </li></ul>www.freelivedoctor.com
  37. 37. Lipogenesis <ul><li>Formation of fat. </li></ul><ul><li>Occurs mainly in adipose tissue and liver. </li></ul><ul><li>Acetic acid subunits from acetyl CoA converted into various lipids. </li></ul>www.freelivedoctor.com
  38. 38. Metabolism of Lipids <ul><li>Lipolysis: </li></ul><ul><ul><li>Breakdown of fat. </li></ul></ul><ul><li>Triglycerides glycerol + fa </li></ul><ul><li>Free fatty acids (fa) serve as blood-borne energy carriers. </li></ul>lipase www.freelivedoctor.com
  39. 39. Beta-oxidation <ul><li>Enzymes remove 2-carbon acetic acid molecules from acid end of fa. </li></ul><ul><li>Forms acetyl CoA. </li></ul><ul><li>Acetyl CoA enters Krebs Cycle. </li></ul>www.freelivedoctor.com
  40. 40. Metabolism of Proteins <ul><li>Nitrogen is ingested primarily as protein. </li></ul><ul><li>Excess nitrogen must be excreted. </li></ul><ul><li>Nitrogen balance: </li></ul><ul><ul><li>Amount of nitrogen ingested minus amount excreted. </li></ul></ul><ul><li>+ N balance: </li></ul><ul><ul><li>Amount of nitrogen ingested more than amount excreted. </li></ul></ul><ul><li>- N balance: </li></ul><ul><ul><li>Amount of nitrogen excreted greater than ingested. </li></ul></ul>www.freelivedoctor.com
  41. 41. <ul><li>Adequate amino acids are required for growth and repair. A new amino acid can be obtained by: </li></ul><ul><li>Transamination: </li></ul><ul><ul><li>Amino group (NH 2 ) transferred from one amino acid to form another. </li></ul></ul>www.freelivedoctor.com
  42. 42. <ul><li>Process by which excess amino acids are eliminated. </li></ul><ul><li>Amine group from glutamic acid removed, forming ammonia and excreted as urea. </li></ul>www.freelivedoctor.com
  43. 43. Deamination <ul><li>Energy conversion: amino acid is deaminated. </li></ul><ul><li>Ketoacid can enter the Krebs Cycle. </li></ul>www.freelivedoctor.com
  44. 44. Use of different energy sources. www.freelivedoctor.com