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28 Cards in this Set
- Front
- Back
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Auxotroph
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mut w/ new growth factor requirement
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Prototroph
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wild-type
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Fastidious
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Many growth requirements
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Protein Secretion
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-prot must have signal seq
-need receptor, translocon to move prot, and E req must be met -20% prots made by bact. |
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Signal seq
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often at amino term end
-phobic alpha helix -C term seq w/ cleavage site sec - unfolded prots tat - folded prots |
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Siderophores
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iron-chelating
-Fe limiting in humans -w/ liver dysfunt - elevated Fe in blood leads to bact inf |
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Bacterial Requirements
major minor |
major - CHOPNS,K,Mg,Ca,Fe,Na,Cl
minor - other elements |
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facultative anaerobe
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grow in presence or absense oxyg
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microaerophiles
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ferment for E, can grow w/ Oxyg less than atmospheric P
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flavoproteins
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react w/ mol oxygen
produce superoxide and hydrogen peroxide |
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superoxide dismutase
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turns superoxide into hydrogen peroxide
-strict anaerobes lack SD |
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catalase
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turns hydrogen peroxide into water and oxygen
-strict anaerobes may lack -some fac anaerobes and aerotolerant lack (use peroxidase - more expensive) |
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How do bact sense environment?
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2 component system:
sensor kinase - HPK Response Regulator HPK senses change and autophosph HPK-P phosph RR RR-P binds DNA or to prot and changes behavior |
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Bacterial Population Growth
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lag phase
log phase - grow @ const rate, characteristic doubling t, standard for experiments stationary phase - lack nutrient death - logarithmic |
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Nutrient Transport
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Water passes cell memb, most philic dont
gram neg have periplasmic prots to transport |
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3 Mechs cross-memb transport
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Carrier-mediated
Phosphorylation-linked Active Transport |
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Carrier-mediated diffusion
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-passive
-mol gradient maintained by contin until of nutrient in cell |
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Phosphorylation-linked transport
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-active
-primarily in sugar transport -mols phosph by transport machinery, make immed avail for ferm or oxid., traps in cell |
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Active Transport
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-E-utilizing
-accums @ far higher conc than med. -couples entry to entry protons -Proton Motive Force -gradient maintained by pumping protons out of cell |
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Proton Motive Force
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E source active transport (and flagella)
-most cells pump protons out creating: -pH or proton gradient -charge gradient -dual E source |
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chemoheterotrophs
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derive E from organic substrates by fermentation or by oxidation w/ mol oxygen
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Respiration
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-organic cmpds oxidized to CO2 and H2O, mol O2 terminal e acceptor
-anything facult. org can ferment, will preferentially oxidize |
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Fermentation
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org cmpds broken down to simpler cmpds
-part free E stored for later use by Ezs which couple steps in rxn to ATP form. -no change in oxidation state compount -Most via Embden-Meyerhof p/w |
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Embden-Meyerhof p/w
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most fermentations use
-carbs oxidized to pyruvic acid -PA must be reduced to balance ox/red |
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End Products E-M p/w
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acids, ethanol and CO2
-Fermentation -strict aerobes will not ferment |
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Anabolism
-Folic Acid metab |
biosynth small mols
-most synth by similar p/ws -few targets for antimicrobials exception: folic acid metab - essential cofactor - most MOs synth own |
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Sulfonamides
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-Affect Folic Acid metab
-sx analogs -compete w/ para-amino benzoic acid - folic acid intermed |
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trimethoprim
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-Target Folic Acid Metab
-inhibits dihydrofolate reductase Ez -cats prod. tetrahydrofolic acid from dihydrofolic acid -high affin for bact. DR and not mammalian |
