Micro Ch. 6
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18 terms
Terms | Definitions |
|---|---|
 Metabolic Cell Needs | C, N, O, H = 95% of dry weight of cell. Also, has H2O. Trace elements like Zn. H most common, needed for H-bonds and e-transfer. |
| Oxygen Requirements | O2 essential for obligate aerobes due to final electron acceptor in transport chain. Obligate anaerobes: O2 will kill them. Susceptible to H2O2 toxicity. Facultative anaerobes: use a bit of O2. O2 not final electron acceptor, uses fermentation pathway. Most aerobes are facultative anaerobes. Aerotolerant anaerobes - don't use O2. Microaerophiles - require 2-10% O2. |
| biofilms | m.o. communities aka slime. cell to cell chemical communication aka quorum sensing allow m.o. to coordinate activity. |
| *4 toxic forms of Oxygen | 1)singlet: 'O2 (very reactive) used by macrophages 2)superoxide radical: O2- aerobes produce superoxide dismutase to detoxify, anaerobes are killed. 3)peroxide anion ([O−O]2-) highly reactive, makes hydrogen peroxide a good antimicrobial agent. deep wounds (against anaerobes) 4)hydroxyl radical (OH) MOST REACTIVE |
| Oxygen Enzymes Reactions | catalase 2 (H2O2) -> 2H2O + O2 (bubbles) peroxidase H2O2 + 2H+ -> 2H2O (no bubbles) superoxide dismutase O2- + O2- + 2H+ -> 2H2O2 + O2 |
| Oxygen Enzymes Function | catalase: breaks down hydrogen peroxide into water and oxygen, hence bubbles. peroxidase: breaks down hydrogen peroxide into water superoxide dismutase: takes two superoxide radical and converts to hydrogen peroxide (which needs to be broken down) and hydrogen |
| Enzymes Aerobes have | Catalase to detoxify peroxide anion. SOD to detoxify superoxide radical. |
| Trace Elements that M.O. need | Zn, Fe, Cu, Mo. Cofactors for enzymes. |
| M.O. Physical Requirements | Temperature pH Osmotic Pressure |
| *Temperature | Min Temp: Lowest temp where metabolism possible, very slow. Optimal Temp: greatest amt of metabolism Max Temp: Temp below perm. protein denaturation. |
| *M.O. Temp. Groups | Psychrophiles (likes cold) best at 15C, die at >20C Mesophiles best at 20-40C includes pathogens Thermophiles best at >45C Hyperthermophiles grow at >80C |
| *pH Groups | Neutrophiles (inclusive of pathogens) best at 6.5-7.5. Acidophiles (e.g. lactobacillus) 3.5. If gone, Candida yeast takes over. Also, Helicobacter pylori, a neutrophile, gram - rod, neutralizes stomach acid urease, makes bicarbonate from urea. Alkalinophiles best in H2O @ 9.0pH. e.g. Vibrio cholerae, gram- rod. likes sewage. |
| Osmolarity and bacteria | hypotonic solution: lyse hypertonic solution: plasmolysis or shrink |
| halophile | salt loving. tolerate up to 20% salt. S. aureus and S. epi, skin is salty. |
| Bacteria and Media General | grow on any media, non-fastidious, e. coli? fastidious bacteria, pathogens need special nutrients like SBA 5% |
| Culture Media Types | Complex: general, often with SBA added Selective: has nutrients favoring some M.O. inhibiting others Differential: shows visible changes in media or colonies Specific: CT-SMAC |
| Generation Time | Doubling time - time required for M.O. cell to grow & divide = period between 'birth' & prod. of offspring. [from book]: the time required for a cell to divide and population to double. |
| Microbial population growth | lag: adjusts to env; no repro; make enzymes log: lots of growth&metabolism. No cell death. stationary: nutrients depleted, wastes accumulate, death causes growth rate to flatline. death: no new nutrients have been added, death rate overcomes growth rate. spores produced. |
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