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

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Sheet1 Page 1 Exam 2 Methods to study microorganisms **Begin EXAM 2 ** h Macronutrients . Elements required in fairly large amounts (Table 5.1- Macronutrients in nature and in culture media) . Collection on required macromolecules . Carbon h Need to make organic compounds such as amino acids, fatty acids, sugars, and nitrogenous bases h Autotrophs . Use CO2 h Heterotrophs . Use organic compounds . Nitrogen h Needed to make amino acids and nitrogenous bases h Nitrogen-fixing microorganisms . Use atmospheric nitrogen (N2) h Non-nitrogen fixers . Use inorganic compounds such as ammonia (NH3) and nitrate (NO3) . Phosphorous h Needed to make nucleic acids and phospholipids h Obtained from phosphate minerals and free phosphates . Sulfur h Needed to make amino acids cysteine and methionine and other vitamins h Obtained from sulfates (SO42-) or Sulfides (S2-)
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Sheet1 Page 2 . Potassium h Needed for some enzymes (mostly protein synthesis) h Obtain from potassium salts . Magnesium h Stabilizes ribosomes, membranes, and nucleic acids and is required by many enzymes h Obtained from various minerals h DNA polymerase needs it . Calcium h Stabilizes cell walls h Endospores- calcium-dipicolinic acid complex . Heat stability of endospores h Obtained from various salts . Sodium h Marine microorganisms h Required for energy production R . Iron h Needed for electron transport chain proteins h Siderophoress- molecules bind iron and transport it into the cell . Examples of siderophores h Enterobactins (5-1b) h E. coli and Salmonella typhimurium h Sequester iron supply from host (could be human or animal)- initiate infection!! h Aquachelin (5-1c) h Marine bacteria
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Page 3 h Micronutrients- trace metals . Elements needed in very small amounts (Table 5.2) h Growth factors- Organic compounds needed in very small amounts by some microorganisms (Table 5.3) h Culture media . Nutrient solutions/solids for microorganisms . Defined or complex? (Table 5.4) h Defined media- contains precise amounts of purified compounds of known composition h Complex media- contains digests of animal or plant products whose extract composition is not known . Selective Media- contains compounds that encourage the growth of some microorganisms and prevent growth of others . Differential media- contains compounds that visibly change when a specific chemical reaction occurs . Enriched media- contains compounds such as blood or serum that encourage the growth of microorganisms by mimicking the natural growthenvironment e . You can mix and match these media!! . Liquid vs. Solid media h Liquid- broth . In tubes/flasks . Used when needing to transfer known amounts of microorganism . Experimental assays h Solid media- same as liquid media but with agar . In Petri dishes-> plated t obtain a pure culture
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This note was uploaded on 12/10/2009 for the course MB 351 taught by Professor Keen during the Spring '08 term at N.C. State.

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

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