BIOL 2P98 Lecture Notes - Trimethylamine N-Oxide, Trimethylamine, Photosynthetic Pigment
5 May 2018
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Chapter 3, 14, 15: Microbial Metabolism & Metabolic Diversity & Functional Diversity
• Metabolism
o Sum of chemical reactions that occur in a cell
o Catabolic reactions: breakdown of organic/inorganic compounds -> production of energy
o Anabolic reactions: synthesis of cell constituents from simpler molecules -> requires energy
• Microbial Cells Must Do Work
o Cell must do work to survive & reproduce
▪ Chemical Work -> synthesis of complex molecules (anabolism)
▪ Transport Work -> take up nutrients, elimination of wastes, maintenance of ion balances
▪ Mechanical Work -> cell motility & movement of structure w/n a cell
o Work requires energy
o Organisms obtain energy from energy sources present in environment & convert it into useful form
▪ Common form is ATP
▪ =energy conservation
• ATP synthase
o Multiprotein complex in membrane that uses PMF to make ATP
o 2 parts: F1 in the cytoplasm & F0 integrated in membrane
o Movement of H+ through F0 rotates c proteins & axle -> induces conformational changes in subunits of F1 which bind ADP + Pi producing
ATP
• Energy Rich Compounds
o Chemical energy released in redox reactions is primarily stored in certain phosphorylated compounds
▪ ATP- prime energy currency
▪ Phosphoenolpyruvate
▪ Free energy is released upon removal (hydrolysis) of phosphate group
o ATP constantly hydrolyzed & resynthesized
o Longer-term energy storage, microorganisms produce
polymers that can be catabolized later to produce ATP
▪ Glycogen, Poly--hydroxybutyrate, elemental
sulfur
• Redox Tower
o Tendency to donate or accept electrons expressed as
reduction potential (E0’)
o Electrons flow spontaneously from lower E0’ to higher
E0’ (down tower)
o Greater difference b/n donor & acceptor = greater ΔG
o
o Think of a water slide
▪ Very top- highest potential energy (best
donors)
▪ Middle- energetically favourable transfer
▪ Bottom- lowest potential energy (best
acceptors)
• Energy Classes of Microorganisms
o Chemotrophs- conserve energy from chemicals
▪ Organic chemicals -> chemoorganotrophs ->
oxidation of glucose (electron donors)
▪ Inorganic compounds -> chemolithotrophs -> oxidation of H2, H2S, NH3, Fe2+ (electron donors)
o Phototrophs- conserve energy from light
▪ have pigments which allow for conversion of light energy to chemical energy
• converts weak electron donors into strong electron donors
▪ oxygenic means oxygen is produced -> cyanobacteria, algae
▪ anoxygenic means no oxygen is yielded -> purple & green bacteria, heliobacteria
o in aerobic respiration, the oxygen accepts electrons and is reduced as water
o in anaerobic respiration, another compound is reduced
o E. coli can use nitrate, fumarate or trimethylamine oxide as an electron acceptor if oxygen is not available
o Why does fish smell bad so quickly?
▪ Trimethylamine oxide reduced to trimethylamine which is a compound with a very fishy smell
• Phototrophs
o Light is used instead of chemicals to drive the transportation of electrons and generate the PMF
▪ Produces ATP via ATPase = photophosphorylation
o Most use CO2 as carbon source = photoautotrophs
▪ If organic compound is used = heterotrophs
o Two main groups of prokaryotic phototrophs
▪ Purple & Green bacteria
• Photosynthetic pigment is bacteriochlorophyll
• Anoxygenic: electrons derived from H2S or H2
▪ Cyanobacteria
• Photosynthetic pigment is chlorophyll
• Oxygenic: electrons derived from H2O which produces O2
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Chapter 3, 14, 15: microbial metabolism & metabolic diversity & functional diversity: metabolism. Sum of chemical reactions that occur in a cell. Catabolic reactions: breakdown of organic/inorganic compounds -> production of energy. Anabolic reactions: synthesis of cell constituents from simpler molecules -> requires energy: microbial cells must do work. Cell must do work to survive & reproduce. Chemical work -> synthesis of complex molecules (anabolism) Atp synthase: multiprotein complex in membrane that uses pmf to make atp. 2 parts: f1 in the cytoplasm & f0 integrated in membrane: movement of h+ through f0 rotates c proteins & (cid:452) axle -> induces conformational changes in (cid:451) subunits of f1 which bind adp + pi producing. Chemical energy released in redox reactions is primarily stored in certain phosphorylated compounds. Free energy is released upon removal (hydrolysis) of phosphate group. Longer-term energy storage, microorganisms produce polymers that can be catabolized later to produce atp.
