MOISTURE - - required in small amounts 2. Special...

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MOISTURE (WATER), OSMOTIC PRESSURE 1. All metabolically active bacteria require presence of water a. Cells largely water b. Most nutrients, wastes soluble in water to cross cell membrane. c. Site of metabolic reactions (cytoplasm) 2. Osmotic pressure a. Exerted by solutes in water b. Increase o.p. outside cell - water leaves cell ( very high o.p. - dehydrates cell ) c. Decreased o.p. outside cell - water enters cell ( very low o.p. - lysis of cell ) d. Halophiles - require the presence of 3% NaCl ( extreme halophiles - 20 to 30% NaCl ) 3. Practical applications ? E. LIGHT ( RADIATION ) 1. Very small group photosynthetic bacteria (cyanobacteria) - require UV light 2. Nonphotosynthetic bacteria (eubacteria) - UV light is lethal (causes mutations) F. NUTRITIONAL REQUIREMENTS 1. Basic requirements for growth : a. Carbon - building blocks of cell components b. Nitrogen - production of proteins, nucleic acids c. Hydrogen - occur in organic compounds d. Oxygen - involved in the production of energy e. Minerals, Trace Elements
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Unformatted text preview: - required in small amounts 2. Special metabolites ( growth factors ) a. Substances required for growth that the cell cannot produce using the basic requirements already listed. ( Ex. : vitamins, amino acids, carbohydrates, blood factors ) b. Organisms may be described as being fastidious. 3. Two types organisms based on source of nutrients : a. Autotrophs - utilize inorganic compounds ( C - CO 2, carbonates; N - NH 4 , N 2 , NO 3 ) b. Heterotrophs - utilize organic compounds ( C - CHO, lipids; N - proteins ) 1). Saprophytes - nonliving organic material 2). Parasites - viable (living) organic material 4. To culture organisms in the laboratory : a. Must provide organism with necessary growth factors b. Various types media - to be described in lab 5. Not all bacteria use same nutrients like humans. Can test for nutritional requirements in lab. Differences in nutritional requirements used for identification, classification...
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This note was uploaded on 01/23/2012 for the course MCB MCB2010 taught by Professor Smith during the Fall '09 term at Broward College.

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MOISTURE - - required in small amounts 2. Special...

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