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29 Cards in this Set
- Front
- Back
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What are the major elements in cells?
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-Carbon (50% dry cell weight)
-Nitrogen (12-14% dry cell weight) -Macronutrients; Posphorus and sulfur |
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Mixotrophy
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Chemical energy source (inorganic). Inorganic H/e- donor. Organic carbon source.
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Nitrogen, phosphorus, and sulfur.
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Nitrogen supplies in numerous ways. Phosphorus usually supplied as inorganic phosphate. Sulfur usually supplied as sulfate via assimilatory sulfate reduction.
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What are the major sources of nitrogen?
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-organic molecules
-ammonia -nitrate via assimilatory nitrate reduction -nitrogen gas via nitrogen fixation |
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Growth factors
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Organic compounds. Essential cell components (or their precursors) that the cell cannot synthesize
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What are some classes of growth factors?
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-amino acids
-purines and pyrimidines -vitamins |
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How can the need for growth factors be used in assays?
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Development of quantiative growth response assays for measuring concentrations of growth factors in a preparation. Industrial production of growth factors by microorganisms.
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How are nutrients transported into the procaryotic cell?
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Some nutrients enter by passive diffusion. Most nutrients enter by:
-facilitated diffusion -active transport -group translocation |
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Passive diffusion
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molecules move from region of high conc. to one of lower conc because of random thermal agitation. H2O, O2, and CO2 often move across membranes this way.
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Facilitated diffusion
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Similar to passive diffusion. Movement of molecules is not energy dependent. Direction is from high to low conc. Size of conc. gradient impacts rate of uptake.
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How does facilitated diffusion differ from passive diffusion?
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Differs because uses carrier molecules (premease), smaller concentration gradient is required for significant uptake of molecules, effectively transports glycerol, sugars, and amino acids.
Facilitated diffusion is more rapid and occurs at a lower concentration. |
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What is active transport?
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Movement of molecules from an area of low concentration to an area of high concentration against the concentration gradient. Movement against the concentration gradient requires the input of energy from an outside source.
Energy-dependent process -ATP -proton motive force -PEP |
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ABC transporters
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ATP-binding Cassette transporters. Observed in bacteria, archae, and eucaryotes.
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What is group translocation?
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Chemically modifies molecule as it is brought into cell. Best known system: transports a variety of phophoenolpyruvate: sugar phosphotransferase system (PTS)
-sugars while phosphorylating them using phosphoenolpyruvate (PEP) as the phosphate donor |
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Group translocation
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-molecules are modified as they are transported across the membrane
-energy dependent process |
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Iron uptake and siderophores
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-Ferric iron is very insoluble so uptake is difficult
-Microorganisms use siderophores to aid uptake -Siderophore complexes with ferric ion -Complex is then transported into the cell |
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Culture media is liquid or solid?
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Both; can be liquid or solid. Solid media are usually solidified with agar.
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Synthetic or Defined Media
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All components and their concentrations are known
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Complex Media
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Contain some ingredients of unknown composition and/or concentration
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Some media components (3) and their descriptions
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(1) peptones
-protein hydrolysates prepared by partial digestion of various protein sources (2) extracts -aqueous extracts, usually beef or yeast (3)agar -sulfated polysaccharide used to solidify liquid media |
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4 types of media
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(1) General purpose media
(2) Enriched media (3) Selective media (4) Differential media |
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General purpose media
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-support the growth of many microorganisms
-tryptic soy agar |
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Enrichment media
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-general purpose media supplemented by blood or other special nutrients
-blood agar |
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Selective media
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-favor the growth of some microorgansims and inhibit the growth of others
-MacConkey agar; selects for gram negative bacteria |
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Differential media
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-distinguished between different groups of microorganisms based on their biological characteristics
-blood agar; hemolytic versus nonhemolytic bacteria -MacCnokey agar; lactose fermenters versus nonfermenters |
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Culture of anaerobes
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-boil medium to remove oxygen
-include reducing agent in the medium -maintain under inert gas |
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Pure culture
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-population of cells arising from a single cell
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What is a pour plate?
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-sample is diluted several times
-diluted samples are mixed with liquid agar -mixture of cells and agar are poured into sterile culture dishes |
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Colony growth
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-most rapid at edge of colony
-slowest at center of colony -in nature, many microorganisms form biofilms on surfaces |
