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Microbial metabolism: pathways, enzymes, energy.
- 1. Chapter 5 -Microbial Metabolism • Metabolism is all of the chemical reactions in an organism. • is the energy-releasing processes. • Occurs when molecular bonds (and thus, molecules) are broken down. • Generates ATP • is the energy-using processes. • Occurs when molecular bonds (and thus, molecules) are formed. • Uses ATP
- 2. Enzymes • Biochemical catalysts •Specific for a chemical reaction • protein portion • Nonprotein component • Coenzyme: Organic cofactor • Holoenzyme: Apoenzyme + cofactor
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- 4. • pH • pHextremes will denature enzymes Factors Influencing Enzyme Activity Figure 5.5b
- 5. • Temperature • Veryhigh temperatures will denature enzymes Factors Influencing Enzyme Activity Figure 5.5a
- 6. • Substrate concentration FactorsInfluencing Enzyme Activity Figure 5.5c
- 7. • Competitive inhibition FactorsInfluencing Enzyme Activity Figure 5.7a, b
- 8. • Noncompetitive inhibition FactorsInfluencing Enzyme Activity Figure 5.7a, c
- 9. • Feedback inhibition: Apathway endproduct (or intermediate) binds to an enzyme in the pathway, stopping the pathway Factors Influencing Enzyme Activity Figure 5.8
- 10. Oxidation-Reduction • is theloss of electrons. • is the gain of electrons. • Redox reaction is an oxidation reaction paired with a reduction reaction.
- 11. The Generation ofATP • ATP is the main energy currency in living cells • Energy released from the transfer of electrons of one compound to another is used to generate ATP.
- 12. Carbohydrate Catabolism • Thebreakdown of carbohydrates to release energy • Glycolysis • Krebs cycle • Electron transport chain
- 13. • The oxidationof glucose to pyruvic acid; produces • Preparatory Stage • 2 ATPs are used • Glucose is split to form two Glyceraldehyde-3- phosphates Glycolysis
- 14. Preparatory Stage Figure 5.12.1 Preparatory Stage Glucose Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-diphosphate Dihydroxyacetone phosphate(DHAP) Glyceraldehyde 3-phosphate (GP) 1 2 3 4 5
- 15. • Energy-Conserving Stage •Two Glyceraldehyde-3-phosphates oxidized to 2 Pyruvic acids • 4 ATP produced • 2 NADH produced
- 16. Energy-Conserving Stage Figure 5.12.2 1,3-diphosphoglycericacid 3-phosphoglyceric acid 2-phosphoglyceric acid Phosphoenolpyruvic acid (PEP) 6 7 8 9 10 Pyruvic acid
- 17. • Preparatory Step: •Pyruvic acid (from glycolysis) is oxidized and decarboyxlated • Acetyl CoA is produced Krebs Cycle
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- 19. Krebs Cycle • Oxidationof acetyl CoA produces 6 NADH and 2 FADH2 • 2 ATP produced; CO2 produced
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- 21. • A seriesof molecules that pass electrons down the chain. (oxidation – reduction reactions) • Energy released can be used to produce ATP by The Electron Transport Chain
- 22. Electron Transport Chainand Chemiosmosis Figure 5.16.2
- 23. Cellular Respiration • Thefinal electron acceptor in the electron transport chain is O2. • The final electron acceptor in the electron transport chain is not O2. Net Yield: • 1 Glucose oxidized aerobically = ~38 ATP • 1 Glucose oxidized anaerobically = much less ATP
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- 25. • Does notrequire oxygen • Does not use the Krebs cycle or ETC • Uses an organic molecule as the final electron acceptor • Alcohol fermentation. Produces ethyl alcohol + CO2 • Lactic acid fermentation. Produces lactic acid. Fermentation
- 26. • Conversion oflight energy into chemical energy (ATP), and the synthesis of sugar • Light-dependent reaction (Light reaction) • Produces ATP and NADPH • Light-independent reaction (Calvin cycle) • Uses ATP and NADPH to make sugar Photosynthesis
- 27. Metabolic Diversity • Autotrophs:Use CO2 as main carbon source • photoautotrophs: Derive energy from sun • chemoautotrophs: Derive energy from inorganic compounds
- 28. Metabolic Diversity • Heterotrophs:Use organic compounds as carbon source • Photoheterotrophs: Derive energy from sun; carbon from organic compounds • Chemoheterotrophs: Generally, derive energy and carbon from organic compounds
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