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Chapter five: microbial metabolism. redox reaction: coupled reactions oxidation-reduction e - removed as part of H atom.

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Presentation on theme: "Chapter five: microbial metabolism. redox reaction: coupled reactions oxidation-reduction e - removed as part of H atom."— Presentation transcript:

1 chapter five: microbial metabolism

2 redox reaction: coupled reactions oxidation-reduction e - removed as part of H atom

3 redox reactions aerobic respiration oxygenic photosynthesis

4 nutritional classification: metabolic strategy aerobic respiration iron oxidizers E source to oxidize e- light/chemical light energy phototroph chemical energy chemotroph carbon source org./inorganic photoheterotrophphotoautotroph carbon source org./inorganic chemoheterotrophchemoautotroph electron source organic/inorganic electron source org./inorganic electron source org./inorganic photoorgano- heterotroph photolitho- heterotroph chemoorgano- heterotroph electron source inorganic photolitho- autotroph oxygenother inorganic electron acceptor org./inorganic fermentation butanediol mixed acid lactic acid alcohol respiration chemoorgano- autotroph chemolitho- autotroph anoxygenic photosynthesis anaerobic respiration sulfur oxidizers oxygenic photosynthesis chemolitho- heterotroph e- acceptor oxygen/other Purple non- Sulfur bacteria PSB, GSB, GNSB Cyanobacteria (plants)

5 classifying respiration & photosynthesis

6 complementary metabolism

7 acquiring ATP: substrate level phosphorylation

8 acquiring ATP: oxidative phosphorylation & chemiosmosis

9 heterotrophy: respiration electron path (oxidation) The ETC process The ETC overview Factors affecting the ETC Switching to fermentation

10 heterotrophy: respiration & fermentation C 6 H 12 O 6 CO 2 NAD + NADH ETC ADP + Plots of ATP 2 H + reduced e- acceptor inorganic e- acceptor C 6 H 12 O 6 pyruvate NAD + NADH substrate Pfew ATP lactic acid ethanol & CO 2 mixed acids butanediol organic pyruvate ferm

11 respiration inorganic e - acceptor does NOT mean O 2 organic mole.  CO 2 fermentation organic e - acceptor organic  organic mole. incomplete H stripping, lower ATP yield heterotrophy: respiration & fermentation The Kreb’s Cycle The Kreb’s Cycle in detail

12 metabolism & media

13 Chapter Five Learning Objectives 1.Discuss redox reactions in biological systems. 2.Identify the redox partners in aerobic and anaerobic respiration and oxygenic and anoxygenic photosynthesis. 3.Correctly identify the carbon, energy and electron source for an organism when given its nutritional classification (e.g., chemoorganoheterotroph). 4.How is ATP generated in both substrate level and oxidative phosphorylation? 5.Why is it so important that the electron transport chain is housed in a lipid bilayer membrane? Why is a terminal electron acceptor so important? 6.What happens in a microorganism if the terminal electron acceptor of the ETC is not available? What molecules build up? What is done with these molecules? 7.Discuss the major differences between respiration and fermentation. What are the four basic kinds of fermentation?

14 chemo-: conversion of chemical E  ATP iron oxidation sulfur oxidation -synthesis: carbon fixation (CO 2  organic molecule) autotrophy: chemosynthesis 2 H + ADP + P ETC ATP NAD + NADH carbon fixation H2SH2S SO H + ADP + P ETC ATP NAD + NADH carbon fixation 2Fe 3+ 2Fe 2+ heterotrophy

15 chemosynthesis: iron oxidation Thiobacillus ferrooxidans chemolithoautotrophy energy = Fe 2+  Fe 3+ electron = same carbon = CO 2  CH 2 O

16 chemosynthesis: sulfur oxidation Sulfolobus acidocaldarius chemolithoautotrophy energy = S 2- (sulfide) / S 2 O 3 2- (thiosulfate)  SO 3 2- (sulfite) electron = same carbon = CO 2  CH 2 O

17 autotrophy: photosynthesisphotosynthesis photo: light E  chemical E – light-dependent (light) reactions – ATP & NAD(P)H “reducing power” synthesis: – light-independent (dark) reactions – carbon fixation: piling e - onto CO 2 H 2 S/H 2 O ADP + P chlorophyll ETC ATP NAD(P) NAD(P)H carbon fixation oxidized chlorophyll heterotrophy

18 non-cyclic photosynthesis in the cyanobacteria cyclic photosynthesis in the purple sulfur bacteria photosynthetic electron photosynthetic electron flow & chemiosmosis Comparing Eukaryotic & Prokaryotic photosynthesis

19 microbial CO 2 fixation

20 photosynthesis compared EukaryotesProkaryotes Algae, PlantsCyanobacteriaGreen BacteriaPurple Bacteria electron donorH2OH2OH 2 O or H 2 Ssulfur compounds O 2 productionoxygenic oxygenic anoxygenic anoxygenic environmentaerobic aerobic anaerobic anaerobic CO 2 fixationCalvin-Benson Reverse Citric Acid (Reverse Kreb’s) Calvin-Benson

21 amphibolism & ATP


23 chemoheterotrophic growth – aerobic respiration – fermentation photoautotrophic growth – anaerobic, anoxygenic photosynthesis H 2 for e - & CO 2 for C photoheterotrophic growth – anaerobic, anoxygenic photosynthesis C 6 H 6 O 4 (succinate) for both metabolic diversity: the non-sulfur purple bacteria

24 chapter 5 learning objectives 1.How is ATP generated in chemosynthesis, photosynthesis and respiration? How is the process different for each and how is it the same? 2.Discuss the redox partners of sulfur and iron oxidizing bacteria. 3.How do non-cyclic and cyclic photosynthesis differ? How does each produce ATP and NADPH/NADH? What is each used for? 4.How is carbon fixed during chemosynthesis and photosynthesis? How is the process similar and how is it different? 5.How do amphibolism, catabolism and anabolism relate to growth and repair in cells?

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