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Unformatted text preview: Antonio Alarcon 9/18/07 MIC 205 Study Guide #2 Microbial Growth o Microbe of the Day Listeria monocytogenes Gram positive (bacillus rod) Common in environment Lives in monocytes (WBCs) Intracellular Can move through cell membrane to spread from cell to cell Psychrotroph Extremophilic organism, capable of growth and reproduction in cold temperatures Listeriosis Bacterial infection caused by gram-positive, motile L. monocytogenes . Noted by fever, aches, GI, or CNS symptoms 2500 cases each year 500 fatal Occurs primarily in newborn infants, pregnant women (30%), and immunocompromised patients (70%) Prevention Pasteurization, avoidance o Growth of Microbes Increase in the number of cells, NOT size One cell becomes colony of millions of other cells Control of microbial growth is important Infection control Growth of industrial and biotech organisms o Factors Regulating Growth Nutrients Chemical substances acquired from the environment Environmental conditions Temperature pH Osmotic pressure O 2 requirements Generation time Time to complete division o Chemical Requirements Water Primary requirement Elements Carbon (50% of cells dry weight) Hydrogen Nitrogen Phosphorous Sulfur o Other trace elements (small/minimal value) Organic Glucose Source of energy Vitamins Coenzymes Amino acids, pruines and pyrimidines o Nutritional Categories Carbon sources CO 2 Autotroph Organic Hetertroph Energy sources Sunlight - Phototroph Organic Chemotroph Saprobe Lives on organic matter of dead organisms Parasite - Lives on organic matter of living host (pathogens) o Osmosis Isotonic Equal tension, intracellular and extra cellular solute concentration are the same Hypotonic Influx of water, intracellular solute concentration greater than extra cellular solute concentration Hypertonic Net diffusion of water out of the cell, intracellular solute concentration lower than extra cellular solute concentration o Facilitated diffusion Diffusion from higher to lower concentration with a carrier molecule, does NOT require energy o Active transport Diffusion from lower to higher, requires energy o Group translocation Diffusion from lower to higher with chemical change o Bulk transport Endocytosis, phagocytosis, pinocytosis o Environmental Factors Influencing Growth Temperature O 2 pH Osmotic Pressure Others: Radiation, atmospheric pressure o Temperature Optima...
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This note was uploaded on 04/03/2008 for the course MIC 205 taught by Professor Decker during the Fall '07 term at University of Arizona- Tucson.
- Fall '07