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| Requirements for microbial growth fall into these two categories? |
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Definition
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| What are the 3 physical requirements |
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Definition
| Temperature, pH, osmotic pressure |
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Term
Temperature requirements for....
Psychrophiles – |
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Definition
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Term
Temperature requirements for....
Mesophiles – |
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Definition
| moderate temp. 37 C= body temp |
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Term
Temperature requirements for....
Thermophiles – |
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Definition
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Temperature requirements for....
Extreme thermophiles |
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Definition
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Term
| Name two extreme thermophiles |
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Definition
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Term
| What is the most common type of bacteria as far as temperature requirements? |
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Definition
| Mesophiles (37 C/ body temp) |
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Term
| What is the optimal pH range for most microbes? |
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Definition
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Term
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Definition
| acidic pH, can tolerate to 1 |
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Definition
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| Most microbes= ______tonic conditions (hypo, hyper, iso) |
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Definition
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Term
| Most microbes ___ to ___% water |
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Definition
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Term
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Definition
| plasma membrane shrinks away from the cell wall & interferes with metabolism |
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Definition
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| Second most important requirement for microbes |
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Definition
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| Carbon is ___% of the dry weight of bacteria |
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Definition
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Term
| Nitrogen is ___% of the dry weight of bacteria |
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Definition
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Term
| Nitrogen is important for _______ |
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Definition
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Term
| Many microbes use N gas from atmosphere = |
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Definition
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Term
| Sulfur & Phosphorus = ___% dry weight of bacteria |
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Definition
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Term
| Surfur (S) is important for? |
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Definition
| amino acid & vitamin synthesis |
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Term
| Phosphorus is important for? |
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Definition
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Term
| Trace elements (Fe++, Zn+, Cu++, etc.) are required in ____amounts. |
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Definition
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Term
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Definition
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Term
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Definition
| Use O2 but grow w/o O2. +O2 use aerobic cellular respiration. -O2= switch to fermentation. |
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Definition
| unable to use O2. Can be toxic. Lack of enzymes to catabolize O2 (C. tetani & C. botulinum. |
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Term
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Definition
Cannot use 02 for growth
Can tolerate O2 presence.
fermentation |
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Term
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Definition
| O2 is required at lower levels than atmospheric O2 |
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Term
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Definition
| nutrient material for growth of microbes in vitro |
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Term
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Definition
| microbes introduced on culture medium |
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Definition
| organisms that grow on culture medium |
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Definition
| initally contains no living organisms. |
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Definition
| complex polysaccharid, from marine algae, thickner in food (ice cream, jellies), culture media |
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Term
| Why is Agar used as a culture media? |
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Definition
not degraded by most bacteria
liquid at 100C
stays liquid at 100-40C |
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Term
| Chemically defined medium |
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Definition
| exact chem. composition is known |
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Definition
| exact chem. composition slightly varies from batch to batch |
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Definition
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Definition
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Definition
culture anaerobes
"reduction" (GER); deplete O2 in medium |
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Definition
| suppress growth of unwanted bacteria and encourage growth of desired bacteria |
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Term
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Definition
selects a certain bacteria by chem reaction.
Ex. blood agar plates= white halo around Steptococcus colonies. |
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Term
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Definition
Favors growth of one bacterium and not others.
is a selective medium, but use low amount of bacteria to start
ex. water sample |
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Term
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Definition
visible growth on a plate
many morphologies
originate from one cell or one group of cells |
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Term
Preserving..
Deep Freezing- temp/how long |
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Definition
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Term
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Definition
freeze drying, water removed
-54 to -72C
years
solid water to vapor water
use high vacuum |
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Term
most bacteria divide by_____
Some bacteria divide by |
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Definition
binary fission
budding (initial sep. from parent cell, bud, bud grows and separates
(ex. yeast) |
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Term
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Definition
| time required for cells to divide and population doubles |
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Term
| generation time for most bacteria |
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Definition
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Term
| each generation expressed as _______ |
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Definition
exponent.
ex. 8 cells, divide 7 times=
8 X 2 (to the 7th power)= 1024
graph on a logarithmic scale |
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Term
| Bacteria growth curve is the growth of cells over _____. |
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Definition
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Term
| 4 phases of bacteria growth |
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Definition
| Lag,log, stationary,death |
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Term
| What is the phase of the most growth |
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Definition
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Term
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Definition
litte of no division,
active metabolism, ex. new medium,
1 hr to days long |
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Term
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Definition
highest metabolic rate
highest susceptibility to drugs, radiation,etc.
exponential growth phase |
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Term
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Definition
decreased growth-nutrient exhausted, accumulation of waste, change pH
slow metabolism |
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Term
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Definition
| log decline, few or no organisms left |
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Term
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Definition
measure # of viable bacteria
minimum of 24 hours= disadvantage |
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Term
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Definition
| colony forming unity, can be one organism or one group of similar organisms. |
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Term
| Each plate = ___ to ___ CFU |
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Definition
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Term
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Definition
dilute high bacterial counts
quantitatively |
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Term
Serial dilutions
if 10,000 bacteria. Dilute 1 ml to __ml liquid to create sample with 1000 bacteria |
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Definition
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Term
| 1,000 to start. Dilute 1 ml to ___ ml liquid to create sample = 100 bacteria |
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Definition
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Term
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Definition
| a dilution placed in a dish and add liquid agar & mix |
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Term
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Definition
| dilution spread over surface of solid agar. use special spread stick. |
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Term
| Filtration used to measure very ____ samples |
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Definition
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Term
| process for filtration 3-steps |
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Definition
vacuum pulls medium through a filter
bacteria caught on filter surface
transfer filter onto agar surface |
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Term
| MPN stands for what? one reason it would be used for measuring bacterial growth? |
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Definition
most probable number
for use with microbes that don't grow well in agar |
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Term
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Definition
Do many dilutions in multiple steps,
count positive results, compare to special chart |
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Term
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Definition
| measured volume of bacterial suspension applied to a special microscope slide with grid. |
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Term
| _____ bacteria are hard to count using direct microbial count method |
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Definition
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Term
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Definition
| electronic counter used for direct microbial count. |
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Term
| direct microbial count... each square represents a certain ______. Count the # of bacteria and multiply by the _____ _____ to get #/ml |
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Definition
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Term
| Turbidity measures bacteria with a ________. _____numbers of bacteria causes the bacterial suspension to become increasingly _____ |
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Definition
Spectophotometer,
higher
cloudy |
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Term
| sensor in the spectophotmeter detects? |
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Definition
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Term
| One problem with using turbidity for measuring bacterial numbers of liquids with relatively small numbers of bacteria is _________ |
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Definition
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Term
| Metabolic activity estimates the number of bacteria by measuring the ____________ |
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Definition
metabolic end products.
ex. H2 gas production, pH |
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Term
| What is the process involved for measuring bacteria using the dry weigh method? |
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Definition
| remove bacteria from medium, purified, dried in desiccator, weighed |
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