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BIO205-CH6-Microgrow
BIO205 - Ch 6 - Microbial Growth - RioSalado - AZ
| Question | Answer |
|---|---|
| Groups of cells large enough to see without microscope. | Colonies - hundreds of thousands of cells |
| 2 main requirements for microbial growth. | Physical (temp, pH, osmotic pressure), & chemical (carbon, nitrogen, oxygen, phosphorus, etc.) |
| 3 temperature classifications of microbes. | (1) psychrophiles (cold-loving), (2) mesophiles (moderate-temp-loving), & (3) thermophiles (heat-loving). |
| Why is it difficult to define psychrophile, mesophile, & thermophile? | Because their ranges & max. growth temps that define them "are not rigidly defined." |
| Which group of bacteria grow well in refrigerator temperature? | Psychrotrophs - "moderate or faculative". |
| Many thermophilic bacteria cannot grow below __ degree Celsius. | 45 |
| Extreme hyperthermophiles have optimum growth temp. of __ degree Celsius. | 80+ |
| Acidophiles can tolerate? | acidity - low pH of 1 even |
| Optimum pH of molds & yeast | 5-6 pH |
| Osmotic loss of water causes __. | plasmolysis |
| Obligate/extreme halophiles | high salt concentrations - lovers |
| Chemoautotrops & photoautotrops get carbon how? | from CO2 |
| Besides carbon, DNA & RNA synthesis require? | nitrogen & phosphorus |
| Half the dry weight of bacterial cell is? | carbon |
| Organisms use nitrogen primarily to form __. | amino group of the amino acids of proteins. |
| Name 3 foods preserved by high osmotic pressure. | salted fish, honey, sweetened condensed milk |
| nitrogen fixation | Using gaseous nitrogen directly from atmosphere (N2) |
| How is sulfur used? | to synthesize sulfer - containing amino acids & vitamins like thiamine & biotin |
| phosphorus is essential for? | Synthesis of nucleic acids & phospholipids of cell membrane, & ATP |
| Potassium, magnesium, & calcium used as __. | cofactors for enzymes |
| Name some trace elements | iron, copper, molybdenum, & zinc - usually cofactors |
| Which bacteria are primary producers at ocean floor? | chemoautotrophs |
| Organisms that require oxygen to live. | obligate aerobes |
| Faculative anaerobes use what? | Oxygen when available but cause use fermentation to continue growth - like E. coli |
| Bacteria unable to use molecular oxygen | Obligate anaerobes - like tetanus & botulism |
| SOD - super oxide dismutase | an enzyme that destroys super oxide (O2) free radicals. |
| Super oxide free radical | A toxic form of oxygen (O2-) formed during aerobic respiration. |
| Singlet oxygen | Highly reactive molecular oxygen (CO2-) |
| Which bacteria lack SOD? | Obligate anaerobes - lack this enzyme to nutralize oxygen. |
| peroxide anion | O2^2- - toxic - part of hydrogen peroxide & benzoyl peroxide - catalase nutralizes. |
| peroxidase | breaks down hydrogen peroxide |
| hydroxyl radical (OH) | Most reactive oxygen form - produced in aerobic respiration |
| Microaerophiles | Aerobic bacteria that grow only in low oxygen concentrations. |
| Organic growth factors | Essential organic compounds an organism cannot synthesize on own & must obtain from environment. Ex - humans needing vitamins. |
| Culture medium | Nutrient material prepared fro growth of microorganism in lab. |
| Inoculum | Microbes introduced to culture medium to initiate growth. |
| culture | microbes that grow & multiply in or on a culture medium. |
| agar | solidifying agent made of a complex polysaccharide derived from marine alga - thickens jellies & ice cream - hard for bacteria to degrade. |
| Chemically defined medium | culture medium with exactly known chemical composition |
| complex media | culture medium with varying chemical composition. |
| nutrient broth | complex medium in liquid form |
| nutrient agar | complex medium in solid form |
| reducing media | Culture medium that removes dissolved oxygen to allow anaerobes to grow - special anaerobic jars, etc. are used. |
| oxyrase | respiratory enzyme used to remove oxygen from petri plates. |
| High CO2 levels are obtained with __ jars. | candle - lighted candle consumes oxygen. |
| capnophiles | microbes that grow better at high CO2 concentrations |
| selective media | suppress growth of unwanted bacteria & encourage growth of desired microbes. |
| defferential media | Solid culture medium used to distinguish colonies of the desired organism grown on same plate as others - Ex: blood agar |
| Enrichment culture | Liquid medium that provides nutrients & environmental conditions favorable to growing specific microbe - selective & used to increase sm. populations. |
| streak plate method is used to obtain? | isloated (pure) culture |
| lypophilization | Freeze-drying - water removed |
| generation time | tme required to double its population |
| What scale is used to graph bacterial growth? | Logarithmic scales |
| Bacterial growth curves show? | Growth of cells over time - lag, log, stationary, & death phase. |
| What occurs during lag phase of growth? | Intense metabolic activity to synthesize reproductive enzymes & molecules. |
| What occurs during log phase of growth? | Period of exponential growth - most active reproductive pahse - most active metabolically - most sensitive to adverse environmental conditions. |
| What occurs during stationary phase of growth? | Growth rate matches death & population stabolizes - metabolic activity slows - equilibrium. |
| What occurs during death phase of growth? | More death than reproduction. |
| Which phase does radiation & antimicrobial drugs interfere with? | Log phase |
| Population numbers are usually recorded as? | cells per milliliter of liquid; or gram of solid material |
| Most frequently used measuring method of bacterial populations. | Plate count - advantage is that it measures number of viable cells, but disadvantage is it takes time. |
| Colony-forming units (CFUs) | Plate counts - colony that results from a chain or bacterial clump instead of just one bacteria. |
| Serial dilutions | Process of diluting a sample several times to make it easier to count. |
| Pour plate method | Method of mixing bacteria into a solid nutrient medium by melting the medium & pouring it into a Petri dish to solidfy. |
| Drawbacks of pour plate method? | Damages heat-senitive microorganisms. |
| Spread plate method | Bacteria added to surface of solid agar medium & spread over the surface with a glass rod. |
| Why is spread plate method better than pour plate? | Bacteria aren't exposed to heat needed to melt medium. |
| Most probable number (MPN) method | Statistical estimation stating that the more bacteria there are, the more dilution needed to produce a zero count. |
| turbidity | How cloudy the medium becomes w/cells - measured by a spectrophotometer - light absorbed by cells. |
Created by:
Ladystorm
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