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Bacterial Metabolism

Bacterial Metabolism. Introduction Enzymes Energy Production Bacterial Catabolism. Bacterial Metabolism. Introduction Metabolism - sum of all chemical reactions in cell Anabolism - reactions that synthesize or “build up” e.g. protein synthesis

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Bacterial Metabolism

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  1. Bacterial Metabolism Introduction Enzymes Energy Production Bacterial Catabolism

  2. Bacterial Metabolism • Introduction • Metabolism - sum of all chemical reactions in cell • Anabolism - reactions that synthesize or “build up” e.g. protein synthesis • Catabolism - reactions that digest or “break down” e.g. starch to glucose

  3. Bacterial Metabolism • Enzyme Introduction • Enzyme Components • Enzyme Mechanism • Factors Influencing Enzymes

  4. Bacterial Metabolism • Enzyme Introduction • Enzymes are biological catalysts • Catalysts are agents which speed up a reaction • Enzymes are very specific • Enzymes are typically proteins • Catalysts work by lowering the activation energy of a reaction

  5. Bacterial Metabolism • Enzymes work to lower activation energy

  6. Bacterial Metabolism • Enzyme Components • Cofactor - nonprotein component that is part of enzyme, e.g. Fe, NAD+, biotin • Apoenzyme - protein portion of enzyme • Holoenzyme - Cofactor plus apoenzyme

  7. Bacterial Metabolism • How enzymes speed up reactions • Proximity • Orientation • Induced fit • Reactive groups • Cofactors

  8. Bacterial Metabolism • Enzyme Mechanism • Substrate binds to active site; lock & key specificity; induced fit • Formation of enzyme-substrate complex • Catalytic activity; localized acid or base or induced fit

  9. Bacterial Metabolism

  10. Bacterial Metabolism • Factors Influencing Enzymes • Temperature • pH • Salt concentration • Inhibitors • Competitive (active site) • Non - Competitive (allosteric) • Feedback Inhibition

  11. Bacterial Metabolism • Energy Production • Oxidation / Reduction reactions • Role of ATP • Phosphorylation • Substrate • Oxidative • Photo-

  12. Bacterial Metabolism • Oxidation / Reduction • Oxidation - loss of electrons • Reduction - gain of electrons • Redox reactions always coupled • Oxidation of reduced carbon tends to be energetically favorable

  13. Bacterial Metabolism • Carbon Oxidation/Reduction • Carbon Dioxide CO2 (+4) • Acid (Formic Acid HCO2) (+2) • Aldehyde (Formaldehyde - H2CO) ( 0 ) • Alcohol (Methanol - H3COH) (-2) • Methane CH4 (-4)

  14. Bacterial Metabolism • Oxidation States • Alcohols • Fats • Organic Acids (acetic acid) • Glucose

  15. Bacterial Metabolism • Role of ATP • ATP  ADP + Pi • Energy intermediate or “currency” • Hydrolysis of ATP “coupled” to energetically unfavorable reactions

  16. Bacterial Metabolism

  17. Bacterial Metabolism • Glucose + Pi Glucose-6-PO4 + H2O ΔG = +13.8 kJ/mol, Keq = 5 x 10-3 • ATP + H20  ADP + Pi ΔG = -30.5 kJ/mol, Keq = 4 x 105 • Glucose + ATP  Glucose-6-PO4 + ADP ΔG = (-30.5 kJ/mol) + (+13.8 kJ/mol) = -16.7 kJ/mol

  18. Bacterial Metabolism • Phosphorylation • Substrate - direct transfer of phosphate from an organic molecule to ADP • Oxidative - ATP generated via chemiosmosis (“proton pump”) and ATP synthase • Photo - light energy from photosynthesis, a modification of chemiosmosis

  19. Bacterial Metabolism • Bacterial Catabolism • Carbohydrate catabolism has two functions: • energy production and/or storage • generation of chemical intermediates • Cellular respiration and fermentation • Includes three processes: • Glycolysis • Kreb’s or Tricarboxylic Acid (TCA) cycle • Electron transport /oxidative phosphorylation

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