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Bacterial Metabolism

Bacterial Metabolism. Metabolism Sum up all the chemical processes that occur within a cell 1. Anabolism: Synthesis of more complex compounds and use of energy 2. Catabolism: Break down a substrate and capture energy. Overview of cell metabolism. Bacterial Metabolism. Autotroph:

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Bacterial Metabolism

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  1. Bacterial Metabolism Metabolism • Sum up all the chemical processes that occur within a cell 1. Anabolism: Synthesis of more complex compounds and use of energy 2. Catabolism: Break down a substrate and capture energy

  2. Overview of cell metabolism

  3. Bacterial Metabolism • Autotroph: Photosynthetic bacterial Chemoautotrophic bacteria • Heterotroph: Parasite Saprophyte

  4. Energy Generating Patterns • After Sugars are made or obtained, they are the energy source of life. • Breakdown of sugar(catabolism) different ways: • Aerobic respiration • Anaerobic respiration • Fermentation

  5. Photosynthesis (1) Higher plants • Light reaction: Photolysis of H2O produce ATP and NADPH • Two photosystem (I & II) Dark fixation: use the production from light reaction (ATP and NADPH) to fix CO2 Reaction: 6CO2 + 6H2O -----> C6H12O6 +6O2 (Light and chloroplast)

  6. Bacteria Photosynthesis i. Only one photosystem can not do photolysis of H2O ii. H2O not the source of electron donor iii. O2 never formed as a product iv. Bacterial chlorophyll absorb light at longer W.L. v. Similar CO2 fixation vi. Only has cyclic photophosphorylation

  7. How the Bacteria synthesize NADPH • Grow in the presence of the H2 gas H2 + NADP+ ------------- NADPH2 hydrogenase • Reverse the electron flow in the e- transport chain H2S S S + NADP+-------- SO4-2 + NADPH2 Succinate Fumarate • Simple non-cyclic photosynthetic e- flow

  8. Chlorophyll a and bacteriochlophyll a(1)

  9. Chlorophyll a and bacteriochlophyll a(2)

  10. Anoxygenic photosynthesis

  11. Anoxygenic versus oxygenic phototrophs(2)

  12. Anoxygenic versus oxygenic phototrophs(1)

  13. Photosynthetic bacteria (1) Chlorobium-green sulfur bacteria Use green pigment chlorophyll Use H2S (hydrogen sulfide), S (sulfur), Na2S2O3 (sodium thiosulfate) and H2 as e- donors. (2) Chromatium-purple sulfur bacteria Use purple carotenoid pigment, same e-donors (3) Rhodospirillum-non sulfur purple bacteria Use H2 and other organic compounds such as isopropanol etc, as e-donors. Reaction: CO2 + 2H2A -----> CH20 + H20 +2A • A is not O

  14. Chemautotroph • Some bacteria use O2 in the air to oxidize inorganic compounds and produce ATP (energy). The energy is enough to convert CO2 into organic material needed for cell growth. • Examples: Thiobacillus (sulfur S) Nitorsomonas (ammonia) Nitrobacter (nitrite) • Various genera (hydrogen etc.)

  15. Aerobic respiration • Most efficient way to extract energy from glucose. • Process: Glycolysis Kreb Cycle Electron transport chain • Glycolysis: Several glycolytic pathways • The most common one: glucose-----> pyruvic acid + 2 NADH + 2ATP

  16. Aerobic respiration • Euk. glucose -----> G-6-P----->F-6-P-----> …... 2 pyruvate +2ATP + 2NADH • Prok. glucose-----> G-6-P------>F-6-P • Process take places during transport of the substrate. Phosphate is from phosphoenolpyruvate (PEP) .....-----> 2 pyruvate +2ATP + 2NADH

  17. Kreb cycle: Pyruvate + 4NAD + FAD -----> 3CO2 +4NADH + FADH GDP + Pi -----> GTP GTP + ADP -----> ATP + GDP • Electron trasnport Chain 4HADH -----> 12 ATP FADH ------> 2 ATP Total 15 ATP Glycolysis -----> 8 ATP • Total equation: C6H12O6 + 6O2 ------> 6CO2 + 6H2O + 38 ATP

  18. Generation of a proton-motive force(1)

  19. Generation of a proton-motive force(2)

  20. Mechanism of ATPase

  21. Anaerobic respiration • Final electron acceptor : never be O2 • Sulfate reducer: final electron acceptor is sodium sulfate (Na2 SO4) • Methane reducer: final electron acceptor is CO2 • Nitrate reducer : final electroon acceptor is sodium nitrate (NaNO3) O2/H2O coupling is the most oxidizing, more energy in aerobic respiration. Therefore, anaerobic is less energy efficient.

  22. Fermentation • Glycosis: Glucose ----->2 Pyruvate + 2ATP + 2NADH • Fermentation pathways a. Homolactic acid F. P.A -----> Lactic Acid eg. Streptococci, Lactobacilli b.Alcoholic F. P.A -----> Ethyl alcohol eg. yeast

  23. c. Mixed acid fermentation P.A -----> lactic acid acetic acid H2 + CO2 succinic acid ethyl alcohol eg. E.coli and some enterbacter d. Butylene-glycol F. P.A -----> 2,3, butylene glycol eg. Pseudomonas e. Propionic acid F. P.A -----> 2 propionic acid eg. Propionibacterium

  24. Alternative energy generating patterns(1)

  25. Alternative energy generating patterns(2)

  26. Alternative energy generating patterns(3)

  27. Alternative energy generating patterns(4)

  28. Energy/carbon classes of organisms

  29. Chlorophyll a and bacteriochlophyll a(3)

  30. Comparison of reaction centers of anoxyphototrophs

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