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10 Cards in this Set
- Front
- Back
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What are the problems faced by microorganisms at low temperatures?
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Lipid membranes become semi-crystalline and lose intregrety at low temperatures, enzyme activity becomes very slow, ice crystal formation can disrupt cell structure
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What are the problems faced by microorganisms at high temps?
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Temp increases, membrane fluidity alters slowly, membrane integrity is lost in fluid and semi crystalline starts.
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How do properties of membrane lipids help microorganisms over come the problems imposed by hot and cold environments
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Lipid concentration- is rich in poly unsaturated fatty acids.
Cyroprotectants- enhance cold tolerance, agents prevent the formation of ice crystals |
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What role do cyroprotectants in adaptation? How do cyroprotectants differ from solutes made by hyper thermophilic microbes
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Cyroprotectants- enhance cold tolerance, they are agents to prevent the formation of ice crystals.
Hyperthermophiles- have solutes that stablize proteins at higher temperatures, most have high internal salt concentrations and some have histone like proteins that help stabilize DNA |
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Thermophilic
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like higher temperatures and has optimal growth temperatures at the enhanced temp. It also follows that there enzymes and proteins will funtion optimally at the enhanced temperature.
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Thermotolerant
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organism can survive higher temps but its optimal growth will be in a more moderate temperature range. Enzymes and proteins will function optimally at the enhanced temperature
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Psychrophiles
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optimal temps at 15 C or below and maxium growth temp 20 C and a minimum growth temp of 0 C or below. May be killed off even by brief exposure to higher temperatures.
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Psychrotolerant
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Organisms grow at 0 C, but have an optima of 20-30 C
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Hyperthermophiles
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Have optium above 75 C and can grow at temperatures above the BP of water.
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Sterilization by Heat Treatment
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Most commonly used methods to control microbial growth. Cells are exposed to moist heat under pressure. Typical condtions are to heat @ 1.1Kg/Cm2 on 15 lbs/in2 pressure for 10-15 minutes result in a temp of 121 C, high temp kills microbes.
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