Lecture 16 PMB

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Microbial Energetics
Candice Young
Flashcards by Candice Young, updated more than 1 year ago
Candice Young
Created by Candice Young over 6 years ago
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Catabolism Accumulate products from original substrates, generate energy electrons are extracted from molecules and transferred to electron carriers (NAD+, NADP+, FAD) which then donate electrons to ETCs or other biosynthetic rxns
Anabolism Accumulate/biosynthesize macromolecules from monomers, consume energy
electron acceptor the substance in a reaction that accepts electrons from some other substance, becoming reduced in the process
electron donor (energy source) The substance in a reaction that donates electrons to another substance, becoming oxidized in the process
Fermentation non-respiratory catabolism in which an organic compound serves as both the electron donor and electron acceptor + ATP is produced by substrate-level phosphorylation
substrate-level phosphorylation production of ATP by transferring a high energy phosphate group from another substrate onto ADP does not require ATPase
respiration catabolism where electrons are extracted from an electron donor and passed down an electron transport chain, generating a proton motive force e- reduce an electron acceptor that is different from the electron donor
oxidative phosphorylation The production of ATP at the expense of a PMF formed by electron transport
proton motive force energized state of the cytoplasmic membrane resulting from the separation of charge and the elements of water (H+ outside and OH- inside) across the membrane
chemoorganotroph use organic material for energy carbon and e- are from same source many bacteria can use organic carbon sources and an alternative (non-O2) e acceptor
chemolithotrophs get electrons and carbon from different source, both chemical typically autotrophs and perform carbon fixation
phototrophs get energy from light, electrons from water or another compound, carbon from organic materials/CO2
electron tower reduced substance in the redox pair at the top has the greatest tendency to DONATE & the oxidized substance at the bottom has the greatest tendency to ACCEPT
reduction potentials E0ʹ [V or mV] taken at pH 7 (the cytoplasm of most cells)
redox couples oxidized form / reduced form
Key principle of redox reactions The reduced substance of a redox couple whose reduction potential is more negative donates electrons to the oxidized substance whose potential is more positive!!
ΔE0ʹ difference in reduction potential between donor and acceptor ΔE0ʹ = (ΔE0ʹ of reduction rxn) - (ΔE0ʹ of oxidation rxn) --> ΔE0ʹ > 0 then reaction is favorable in direction written
Conversion of potential difference to free energy ΔGoʹ = -nFΔE0ʹ n is the number of electrons transferred in the reaction (given on the electron tower) and F is the faraday constant (96.5 kJ/V)
How do bacteria store the energy they get from redox reactions? Bacteria store energy from this by: 1) Using a proton gradient across the cytoplasmic membrane 2) Having high energy compounds that are used to power unfavorable reactions (ie. phosphoenopyruvate, 1,3-Biphosphoglycerate, ATP, ADP)
NAD+ and FAD common currency for oxidation and reduction, used by enzymes to oxidize/reduce different substrates
¯\_(ツ)_/¯ for metabolism Needs 1: an energy source 2: an electron donor 3: an electron acceptor 4: a nutrition source
glucose --> CO2 O2 --> H2O glucose is the electron donor/energy source/carbon source oxygen is the electron acceptor
light and acetate come in to organism H2S --> S0 light = energy source acetate = carbon source electron donor = H2S electron acceptor = acetate
acetate --> CO2 O2 --> H2O O2 = electron acceptor Acetate = energy source Acetate = electron donor Acetate = carbon source --> some acetate used directly to make ATP, other times ATP is used to reduce acetate into needed macromolecules
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