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31 Cards in this Set
- Front
- Back
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Microbial growth
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-Increase in a population of microbes
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The reproduction of a microorganism results in
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-growth
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Most common nutrients contain necessary elements such as
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-carbon, oxygen, nitrogen, and hydrogen
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Trophe is greek for
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Nourishment
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What are the two groups of organisms based on source of carbon
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-Autotrophs
-Heterotrophs |
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What are the two groups of organisms based on source of energy
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-Chemotrophs
-Phototrophs |
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Obligate Aerobes
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MUST grow in the presence of oxygen
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Obligate Anaerobes
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-Must grow in the absence of oxygen
-unable to tolerate the active oxygen |
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Facultative anaerobes
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able to use oxygen, but can switch to fermentation when needed
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Aerotolerant anaerobes
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Do not need oxygen but can tolerate it
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Microaerophiles
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require oxygen to survive, only tolerates low levels of it
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What are the four forms of active oxygen
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-Singlet oxygen
-Superoxide radicals -Peroxide anion -Hydroxyl radical |
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What effect can temperature have on protiens
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it will DENATURE them, change the shape
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Effect of temperature on lipid-containing membranes of cells and organelles
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-If too low, membranes become rigid and fragile
-If too high, membranes become too fluid |
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Neutrophiles grow best in
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-a narrow range around neutral pH
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Acidophiles grow best in
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-acidic habitats
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Alkalinophiles live in
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-alkaline soils and water
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Two physical effects of water
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-Osmotic pressure
-Hydrostatic pressure |
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Osmotic pressure
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-The pressure exerted on a semipermeable membrane by a solution containing solutes that cannot freely cross membrane
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Hypertonic environment
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Net movement of H20 out
of cell |
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Hypotonic environment
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Net movement of H20
Into cell |
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biofilm
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is an aggregate of microorganisms in which cells adhere to each other on a surface
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Organisms live in association with different species in a biofilm, 3 types
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-Antagonistic relationships
-Synergistic relationships -Symbiotic relationships |
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what is the purpose of the extracellular matrix in a biofilm
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-Adheres cells to one another
-Allows attachment to a substrate -Sequesters nutrients -May protect individuals in the biofilm |
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Defined media
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media in which you know all of the nutrients
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Complex media
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media in which you do no know all of hte nurtients
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Selective media
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media that only allows for certin organisms to grow
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Differential media
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distinguish one microorganism type from another growing on the same medi
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Anaerobic media
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media that allow for the growth of anaerobes
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Preserving Cultures-3 wys
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-Refrigeration
Stores for short periods of time -Deep-freezing Stores for years -Lyophilization (freeze drying) Stores for decades |
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Generation Time
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-Time required for a bacterial cell to grow and divide
-Shorter generation time -> faster growth |
