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Bacterial Metabolism Metabolism – Sum up all the chemical processes that occur within a cell 1. Anabolism: Synthesis of more complex compounds and use.

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Presentation on theme: "Bacterial Metabolism Metabolism – Sum up all the chemical processes that occur within a cell 1. Anabolism: Synthesis of more complex compounds and use."— Presentation transcript:

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

5 Photosynthesis (1) Higher plants – Light reaction: Photolysis of H 2 O produce ATP and NADPH – Two photosystem (I & II) Dark fixation: use the production from light reaction (ATP and NADPH) to fix CO 2 Reaction: 6CO 2 + 6H 2 O -----> C 6 H 12 O 6 +6O 2 (Light and chloroplast)

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8 Bacteria Photosynthesis i. Only one photosystem can not do photolysis of H 2 O ii. H 2 O not the source of electron donor iii. O 2 never formed as a product iv. Bacterial chlorophyll absorb light at longer W.L. v. Similar CO 2 fixation vi. Only has cyclic photophosphorylation

9 How the Bacteria synthesize NADPH Grow in the presence of the H 2 gas H 2 + NADP NADPH 2 hydrogenase Reverse the electron flow in the e- transport chain H 2 S S S + NADP SO NADPH2 Succinate Fumarate Simple non-cyclic photosynthetic e - flow

10 Chlorophyll a and bacteriochlophyll a (1)

11 Chlorophyll a and bacteriochlophyll a (2)

12 Anoxygenic photosynthesis

13 Anoxygenic versus oxygenic phototrophs (2)

14 Anoxygenic versus oxygenic phototrophs (1)

15 Photosynthetic bacteria (1) Chlorobium-green sulfur bacteria Use green pigment chlorophyll Use H 2 S (hydrogen sulfide), S (sulfur), Na 2 S 2 O 3 (sodium thiosulfate) and H 2 as e- donors. (2) Chromatium-purple sulfur bacteria Use purple carotenoid pigment, same e-donors (3) Rhodospirillum-non sulfur purple bacteria Use H 2 and other organic compounds such as isopropanol etc, as e-donors. Reaction: CO 2 + 2H 2 A -----> CH H A A is not O

16 Chemautotroph – Some bacteria use O 2 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.)

17 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

18 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

19 – 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: C 6 H 12 O 6 + 6O > 6CO 2 + 6H 2 O + 38 ATP

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25 Generation of a proton-motive force (1)

26 Generation of a proton-motive force (2)

27 Mechanism of ATPase

28 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.

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32 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

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35 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

36 Alternative energy generating patterns (1)

37 Alternative energy generating patterns (2)

38 Alternative energy generating patterns (3)

39 Alternative energy generating patterns (4)

40 Energy/carbon classes of organisms

41 Chlorophyll a and bacteriochlophyll a (3)

42 Comparison of reaction centers of anoxyphototrophs

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