Exam 2 - Exam 2 Methods to study microorganisms*Begin EXAM...

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Exam 2 Methods to study microorganisms **Begin EXAM 2 ** 1. Macronutrients o Elements required in fairly large amounts (Table 5.1- Macronutrients in nature and in culture media) o Collection on required macromolecules o Carbon Need to make organic compounds such as amino acids, fatty acids, sugars, and nitrogenous bases Autotrophs Use CO 2 Heterotrophs Use organic compounds o Nitrogen Needed to make amino acids and nitrogenous bases Nitrogen-fixing microorganisms Use atmospheric nitrogen (N 2 ) Non-nitrogen fixers Use inorganic compounds such as ammonia (NH 3 ) and nitrate (NO 3) o Phosphorous Needed to make nucleic acids and phospholipids Obtained from phosphate minerals and free phosphates o Sulfur Needed to make amino acids cysteine and methionine and other vitamins Obtained from sulfates (SO 4 2- ) or Sulfides (S 2- ) o Potassium Needed for some enzymes (mostly protein synthesis) Obtain from potassium salts o Magnesium Stabilizes ribosomes, membranes, and nucleic acids and is required by many enzymes Obtained from various minerals DNA polymerase needs it o Calcium Stabilizes cell walls Endospores- calcium-dipicolinic acid complex Heat stability of endospores Obtained from various salts o Sodium Marine microorganisms Required for energy production o Iron Needed for electron transport chain proteins Siderophoress- molecules bind iron and transport it into the cell
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o Examples of siderophores Enterobactins (5-1b) E. coli and Salmonella typhimurium Sequester iron supply from host (could be human or animal)- initiate infection!! Aquachelin (5-1c) Marine bacteria 2. Micronutrients- trace metals o Elements needed in very small amounts (Table 5.2) 3. Growth factors- Organic compounds needed in very small amounts by some microorganisms (Table 5.3) 4. Culture media o Nutrient solutions/solids for microorganisms o Defined or complex? (Table 5.4) Defined media- contains precise amounts of purified compounds of known composition Complex media- contains digests of animal or plant products whose extract composition is not known o Selective Media- contains compounds that encourage the growth of some microorganisms and prevent growth of others o Differential media- contains compounds that visibly change when a specific chemical reaction occurs o Enriched media- contains compounds such as blood or serum that encourage the growth of microorganisms by mimicking the natural growth environment o You can mix and match these media!! o Liquid vs. Solid media Liquid- broth In tubes/flasks Used when needing to transfer known amounts of microorganism Experimental assays
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Solid media- same as liquid media but with agar In Petri dishes-> plated t obtain a pure culture In tubes Slants- to maintain cultures Deeps- for experimental assays o For pictures check lab manual!! 5.
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This note was uploaded on 03/30/2008 for the course BIOL 2051 taught by Professor Brininstool during the Fall '07 term at LSU.

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Exam 2 - Exam 2 Methods to study microorganisms*Begin EXAM...

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