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Cell Metabolism Part 1
 

Cell Metabolism Part 1

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    Cell Metabolism Part 1 Cell Metabolism Part 1 Presentation Transcript

    • Electron Transport and Oxidative Phosphorylation It all reduces down to water. www.freelivedoctor.com
    • Mitochondria
      • outer membrane relatively permeable
      • inner membrane permeable only to those things with specific transporters
        • Impermeable to NADH and FADH 2
        • Permeable to pyruvate
      • Compartmentalization
        • Kreb's and β-oxidation in matrix
        • Glycolysis in cytosol
      www.freelivedoctor.com
    • Most energy from Redox
      • electrons during metabolic reactions sent to NAD and FAD
        • Glycolysis
          • In cytosol
          • produces 2 NADH
        • Pyruvate dehydrogenase reaction
          • In mitochondrial matrix
          • 2 NADH / glucose
        • Krebs
          • In mitochondrial matrix
          • 6 NADH and 2 FADH 2 / glucose
      www.freelivedoctor.com
    • Electron Transport Chain
      • Groups of redox proteins
        • On inner mitochondrial membrane
        • Binding sites for NADH and FADH 2
          • On matrix side of membrane
          • Electrons transferred to redox proteins
          • NADH reoxidized to NAD +
          • FADH 2 reoxidized to FAD
      www.freelivedoctor.com
    • 4 Complexes
      • proteins in specific order
      • Transfers 2 electrons in specific order
        • Proteins localized in complexes
          • Embedded in membrane
          • Ease of electron transfer
        • Electrons ultimately reduce oxygen to water
          • 2 H + + 2 e - + ½ O 2 --  H 2 O
      www.freelivedoctor.com
    • Electron Transport Chain www.freelivedoctor.com
    • Complex 1
      • Has NADH binding site
        • NADH reductase activity
          • NADH -  NAD +
        • NADH ---> FMN--->FeS---> ubiquinone
        • ubiquinone ---> ubiquinone H 2
        • 4 H + pumped/NADH
      www.freelivedoctor.com
    • Electron Transport Chain www.freelivedoctor.com
    • Complex II
      • succinate ---FAD—ubiquinone
        • Contains coenzyme Q
        • FADH 2 binding site
          • FAD reductase activity
          • FADH 2 --  FAD
      www.freelivedoctor.com
    • Electron Transport Chain www.freelivedoctor.com
    • Complex III
      • ubiquinone -  ubiquinone ox
      • while cyt C gets reduced
      • Also contains cytochromes b
        • proton pump 4H +
          • Adds to gradient
            • 8 H + / NADH
            • 4 H + / FADH 2
      www.freelivedoctor.com
    • Electron Transport Chain www.freelivedoctor.com
    • Complex IV
      • reduction of oxygen
      • cytochrome oxidase
      • cyt a+a3 red ---> oxidized state
      • oxygen ---> water
        • 2 H + + 2 e - + ½ O 2 --  2 H 2 O
        • transfers e - one at a time to oxygen
      • Pumps 2H + out
        • Total of 10 H + / NADH
        • Total of 6 H + / FADH 2
      www.freelivedoctor.com
    • Totals
      • Proton gradient created as electrons transferred to oxygen forming water
        • 10 H + / NADH
        • 6 H + / FADH 2
      www.freelivedoctor.com
    • Electron Transport Chain www.freelivedoctor.com
    • Generation of ATP
      • Proton dependant ATP synthetase
        • Uses proton gradient to make ATP
        • Protons pumped through channel on enzyme
          • From intermembrane space into matrix
          • ~4 H + / ATP
        • Called chemiosmotic theory
      www.freelivedoctor.com
    • Totals
      • NADH
        • 10 H + X 1 ATP = 2.5 ATP
        • 4 H +
        • FADH 2
        • 6 H + X 1 ATP = 1.5 ATP
        • 4 H +
      www.freelivedoctor.com
    • Total ATP from mitochondrial matrix
      • Pyruvate dehydrogenase
        • NADH ……………………………….2.5 ATP
      • Krebs
        • 3 NADH X 2.5 ATP/NADH ……….7.5 ATP
        • FADH 2 X 1.5 ATP / FADH 2 ……….1.5 ATP
        • GTP X 1 ATP / GTP …………….. 1.0 ATP
          • (from a separate reaction)
          • Total …………….12.5 ATP
          • (Per glucose = X 2 = 25 ATP)
      www.freelivedoctor.com
    • What about NADH from glycolysis?
      • NADH made in cytosol
      • Can’t get into matrix of mitochondrion
      • 2 mechanisms
        • In muscle and brain
          • Glycerol phosphate shuttle
        • In liver and heart
          • Malate / aspartate shuttle
      www.freelivedoctor.com
    • Glycerol Phosphate shuttle www.freelivedoctor.com
    • Glycerol phosphate shuttle
      • In muscle and brain
      • Each NADH converted to FADH 2 inside mitochondrion
        • FADH 2 enters later in the electron transport chain
        • Produces 1.5 ATP
      www.freelivedoctor.com
    • Total ATP per glucose in muscle and brain
      • Gycerol phosphate shuttle
        • 2 NADH per glucose -  2 FADH 2
        • 2 FADH 2 X 1.5 ATP / FADH 2 ……….3.0 ATP
        • 2 ATP in glycoysis ……………………2.0 ATP
        • From pyruvate and Krebs
          • 12.5 ATP X 2 per glucose …………….. 25.0 ATP
              • Total = 30.0 ATP/ glucose
      www.freelivedoctor.com
    • Malate – Aspartate Shuttle www.freelivedoctor.com
    • Malate – Aspartate Shuttle in cytosol
      • In liver and heart
      • NADH oxidized while reducing oxaloacetate to malate
        • Malated dehydrogenase
      • Malate crosses membrane
      www.freelivedoctor.com
    • Malate – Aspartate Shuttle in matrix
      • Malate reoxidized to oxaloacetate
        • Malate dehydrogenase
        • NAD + reduced to NADH
      • NADH via electron transport yields 2.5 ATP
      Mlate – Aspartate Shuttle in cytosol www.freelivedoctor.com
    • Total ATP per glucose in liver and heart
      • Malate – Aspartate Shuttle
        • 2 NADH per glucose -  2 NADH
        • 2 NADH X 2.5 ATP / NADH…………5.0 ATP
        • 2 ATP from glycolysis………………..2.0 ATP
        • From pyruvate and Krebs
          • 12.5 ATP X 2 per glucose …………….. 25.0 ATP
              • Total = 32.0 ATP/ glucose
      www.freelivedoctor.com
    • Summary
      • Total ATP / glucose
        • Muscle and brain 30.0 ATP
          • Uses glycerol phosphate shuttle
        • Heart and liver 32.0 ATP
          • Uses malate aspartate shuttle
      www.freelivedoctor.com