Microbiology V

Pregunta	Respuesta
What is a psychrophile?	MO that has an optimal growth at 15c or lower Max=20c
Which extremophiles survives at -12c?	Psychromona
Lowest enzyme temperatures	Some enzymes at -20c
What climates does a psychrotolerant MO?	Can grow at 0c Optima= 20c-40c Found in temperate climates
What are snow algae?	Chlamydomonas nivalis surface of permanent snowfall Red-pigmented spore in bad conditions
Protein adaptations to cold	their 1' structure has more polar amino acids, fewer weaker bonds 2' has more a-helix than b-sheets, gives protein greater flexibility Cold shock proteins
Membrane adaptations to cold	High unsaturated and short fatty acid chain content
What do cells produce to prevent ice crystals?	Cryoprotectants, solutions that prevent formation of ice crystals in cells.
What optimum temperature do thermophiles grow at?	45'c
Hyperthermophile charas	found in hot springs prokaryotic only Short generation times
Which extremophile is the most thermotolerant?	Methanopyrus, 122'c.
Species gradient	As boiling water leaves hot springs it cools, creating a thermal gradient Different species grow at different temperatures along the gradient
Thing learned from studying species gradients	Pros can grow at much higher 'c than Eu's Archaea are most thermophilic of all pro
Do photoT or non-photoT org tolerate heat better?	Non-photo Found from studying species gradients
Heat stable protein adaptations	More ionic bonds between basic/acidic aa
DNA protections for hyperthermophiles (2)	Highly hydrophobic to Increased DNA stability Reverse DNA gyrase induces positive supercoils
Membrane adaptations in thermophiles	More saturated fatty acid, form a strong hydrophobic environment Longer chain FA= increased surface area=increased mpt
membrane adaptions in HYPERthermophiles	Don't have FA Have c40 isoprenes that are ether bonded to glycerol phosphate Forms a lipid monolayer
Describe the characteristics of acidophiles	Grow at pH 5.5 or below Max = 7
Why is an optima of 1 rare?	scarcity of pH 1 in nature
What cellular component is crucial for acidophiles?	Stability of cytoplasmic membrane is critical A high [H*] is required for membrane stability
Describe the characteristics of alkaliphiles	pH 8+ or above Max = pH 11 Cytoplasmic pH near neutrality Use Na+ gradients instead of H+
Bacteria in saltlakes	Solute potential is very negative constant hypertonic conditions
"physiological drought"	Extremely hard to extract water from surroundings
What's the name for salt loving and salt tolerant bacteria?	Halophiles Halotolerant
How do halophiles adapt to salty conditions?	Increase internal solute potential using compatible solutes
What sort of solutes?	Solutes that are highly soluble but don't interfere with cellular metabolism, such as proline residues.
What is characteristic of a compatible solute?	Compatible solutes aren't charged and won't strip the solvent shell of proteins
Name some examples of compatible solutes (5)	Sucrose, Trehalose, Glycine, Betaine, Glycerol

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