Download - 6. Microbial Metabolism.220.IO
-
7/29/2019 6. Microbial Metabolism.220.IO
1/4
1
BIO 220 INSTRUCTORS OUTLINE
Microbial Metabolism
Terms:
Enzyme
Active Site
Allosteric Site
Allosteric Activation
Allosteric Inhibition
Role of enzymes increasing rate of reactions
Sequester substrates
Create microenvironment
Lower Activation Energy (EA) of reaction
Enzymes do not change G of reaction
Enzymes remain chemically unchanged upon completion of reaction
Substrate
End Product
Co-Enzyme
Co-Factor
Metabolism
Catabolism
Anabolism
Gibbs Free Energy
Endergonic reaction
Exergonic reaction
Activation Energy (EA)
Hydrolysis reaction
Condensation reaction
Redox reactions
Oxidation
Reduction
Short term sources of energy
Long term sources of energy
Chemoorganotrophs
Aerobic Respiration (O2 as terminal electron acceptor)
-
7/29/2019 6. Microbial Metabolism.220.IO
2/4
2
Anaerobic Respiration (Inorganic ions as terminal electron acceptor; NO32-
,
Hg2+
, etc.)
Fermentation (endogenous organic molecule as terminal electron acceptor)
C6H12O6 + 6O2 -----> 6 CO2 + 6 H20
Glycolysis
Citric Acid Cycle
Electron Transport
Chemiosmosis
Redox Potential
The difference in energy from electron donor to terminal electron acceptor
Compare O2 vs NO32-
Substrate Level Phosphorylation
Synthesis of ATP using phosphorylated organic molecule as donor
Glycolysis
Citric Acid Cycle
Oxidative Phosphorylation
Phosphorylation of ADP with inorganic phosphate to produce ATP
Catalyzed by ATP SynthaseEnzyme located in Plasma Membrane
Reaction occurs on cytoplasmic surface
Energy for reaction provided by Proton Motive Force
Glycolysis
Glucose -> 2 Pyruvate
Occurs in cytoplasm
Series of 10 reactions
1
st
5 reactions- energy investment2
nd5 reactions- energy payoff
2 net ATP yield via Substrate Level Phosphorylation
NADH generated as carbon is oxidized
Decarboxylation of Pyruvate yields CO2 + Acetlyl-CoA + NADH
Citric Acid Cycle
-
7/29/2019 6. Microbial Metabolism.220.IO
3/4
3
Acetyl group of Acetyl-CoA donated to a series of redox reactions
Ultimate product is CO2Oxidation of carbon produces NADH and FADH2
ATP via Substrate level Phosphorylation
Occurs in cytoplasm + 1 enzyme (Succinate Dehydrogenase) on plasma
membrane
Electron Transport Chain
Series of enzymes located in Plasma Membrane
Oxidizes NADH and FADH2 generated during Glycolysis, Citric Acid Cycle
Ultimately donates electrons to oxygen forming water
Decreasing Free Energy and increasing Electronegativity keep electron flow
unidirectional
Some enzymes accept electrons + hydrogen
Hydrogen ions translocated unidirectionally across membrane
Some carriers accept electrons only
Proton Motive Force
Chemical and electrical component
Used for Motility, Transport, ATP Synthesis via Oxidative Phosphorylation
Chemiosmosis
Link between Electron Transport Chain and Oxidative Phosphorylation
Uncouplers- 2,4 Dinitrophenol
Inhibitors electron transport
Cyanide, Carbon MonoxideInhibitor of ATP Synthase- Oligomycin
Anaerobic Respiration
Nitrate Reduction
Utilizes Glycolysis, Citric Acid Cycle, Electron Transport Chain, ATP Synthase
Energy yield slightly less than aerobic respiration due to differences in redox
potential
Sulfate ReductionH2 Electron donor, oxidized by Hydrogenase
Adenosine phosphosulphate + SO32-
act as electron acceptors
ATP Synthase
See figure 17.39
Fermentation
-
7/29/2019 6. Microbial Metabolism.220.IO
4/4
4
Reduction of Pyruvate or other compounds to regenerate NAD+
Biosynthestic Pathways
Glycolysis, Citric Acid Cycle pathways contain precursors to nucleic acids, amino acids
See figure 5.25d, 5.26