1. CHAPTER 5 MICROBIAL METABOLISM

2. Energy –Chemical work –Transport work –Mechanical work Laws of thermodynamics –1 st –2 nd – entropy

3. Two fundamental tasks required for growth and reproduction –Catabolism –Anabolism

4. Metabolism –Amazing diversity but also unity Ordered, enzyme-mediated pathways ATP Redox

5. Catabolic reactions –hydrolytic, exergonic (-ΔG) –Keq>1, spontaneous –Cellular respiration Provides precursor molecules and energy for anabolic reactions

6. Anabolic reactions –dehydration synthesis, endergonic (+ΔG) –Keq<1, not favorable –protein synthesis Consumes energy and precursor molecules in the biosynthesis of macromolecules

7. Amphibolic reactions

8. Energy of Activation (E A ) Catalysts (influence reaction rate): –Temperature –Substrate Concentration –Enzymes – biological catalysts

10. Enzymes: All protein or holoenzymes –Apoenzyme + Cofactor (coenzyme)

11. Characteristics of enzymes –do not make reactions happen that could not happen on their own –not permanently altered or used up –substrate-specific –Function is based on structure

12. Six functional categories of enzymes:

13. Unconventional Enzymes Ribozymes –Novel type of RNA Extremozymes –Have molecular applications

14. Mechanism of Enzymatic Action Induced Fit model

16. Factors influencing enzyme activity Denaturing stresses –Heat, pH, UV radiation, chemicals Substrate concentration Competitive inhibition Non-competitive (allosteric) inhibition

19. Feedback Inhibition Negative allosteric effection

20. Reduction-Oxidation Reactions Redox reactions liberate energy –always coupled –oxidation (electron donor) –reduction (electron acceptor) Standard reduction potential (E`O) Reducing power (potential energy)

21. Reduction of NAD – common electron carrier Electrons and protons are typically removed together The equivalent of a hydrogen atom

22. NAD and FAD are common electron carriers

23. E’ 0 of various biologically important redox couples Electrons moving toward less negative acceptors release free energy Amount of energy released correlates with magnitude of difference in E’ 0

24. ATP Synthesis Free energy used to phosphorylate ADP forms ATP – metabolic money!

25. Substrate level phosphorylation –chemical energy Oxidative phosphorylation –energy from proton motive force Photophosphorylation –radiant energy

26. Heterotrophic Metabolism Oxidize energy (electron) rich organic molecules Typically utilize carbohydrates –Glucose (C 6 H 12 O 6 ) is #1 source

27. Three possible pathways based on final electron receptor –Aerobic respiration – exogenous (oxygen) –Anaerobic respiration – exogenous –Fermentation – endogenous organic

28. pathways are amphibolic and provide Energy Reducing power Precursor metabolites

29. –Respiration uses reducing power to generate ATP NADH and FADH 2 provide electrons to power proton motive force Terminal electron acceptor varies –Oxygen in aerobic respiration –Anaerobic respiration uses alternate inorganic molecule

31. GLYCOLYSIS Embden-Meyerhof Pathway Common pathway Glucose (6C) partially broken down into 2 molecules of pyruvate (3C) –Anerobic; cytoplasm 2 NADH; 4 ATP 2 ATP consumed; so net gain of 2 ATP –Substrate level phosphorylation

34. Pentose phosphate pathway –Produces many intermediate materials for other pathways glyceraldehyde 3-phosphate, fructose 6- phosphate, ribulose 5-phosphate If only 5 carbon sugars are available it can biosynthesize 6 carbon sugars –Major contributor to biosynthesis reducing power in NADPH vital precursor metabolites for anabolic pathways intermediates may be used to generate ATP

35. Pentose phosphate pathway

36. Entner-Doudoroff pathway –Alternate pathway to glycolysis –typically not seen in G+ bacteria –major contributor to biosynthesis reducing power as NADH and NADPH vital precursor metabolites for anabolic pathways

37. Entner-Doudoroff pathway