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49 Cards in this Set
- Front
- Back
What is the equation for resolution?
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Resolution (diameter of the smallest visible object) =
(lambda, wavelength)/ 2*(N.A. object, numerical aperature) |
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Define parfocal.
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A set of lenses whose focal points lie in the same plane
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What are the 10 microscope problems?
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Slide is upside down
Lens locked into safety position Oil on low power lenses No immersion oil used Focus on wrong thing Phase contrast filter in wrong position Magnification too low Not enough light Too much light Cord in way |
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What function does oil immersion serve?
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Oil has nearly the same refractory index as the glass slide (allowing more light to come through?)
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What are the 2 types of culture media?
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Complex and
Chemically-defined (synthetic) |
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Name some qualities of complex media.
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Provides excess of all nutrients
Minimize lag, maximize growth High productivity Permits many organisms to grow |
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Name some qualities of chemically-defined media.
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Great value in studying the minimum nutritional requirements of a particular microorganism
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What is the process by which one handles materials without introducing unwanted microorganisms?
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Aseptic technique
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What simple device is used for sterile transfer of microorganisms?
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Inoculating loop
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Why is a three-phase streak useful?
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You can dilute a mixed culture and be able to select one colony/CFU
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What are the 2 type of oblique light microscopy?
Name the importance of each. |
Reflected - allows you to see morphology of colonies inoculated on a dark agar
Transmitted - allows you to see the interior structure of colonies |
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What is another name for oblique, transmitted light microscopy?
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The "Henry technique"
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What is a mordant?
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A mordant is a compound that sets a dye, i.e. iodine
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What are the 4 reagents used in a Gram Stain? (in order)
Describe each reagent's purpose |
1 - Crystal violet - primary stain
2 - Iodine - mordant (set dye) 3 - Ethanol - decolorizing agent of gram (-) negative cells 4 - Safranin - counterstain for gram (-) negative cells |
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Describe peptidoglycan levels for both Gm+ and Gm- cells.
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Gm+ have cell walls with THICK peptidoglycan layers
Gm- have cell walls with THIN peptidoglycan layers |
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What color are Gm+ and Gm- cells, respectively, after a gram stain?
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Gm+ = purple
Gm- = pink |
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What is a "pure culture" of a bacterium?
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Only one bacterial strain is present
Created from one CFU |
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List the 5 (FIVE) categories that microorganisms can be divided into, based on their oxygen tolerance.
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Obligate aerobe
Microaerophile Facultative anaerobe Aerotolerant anerobe Obligate anaerobe |
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What are the 4 (FOUR) types of population interactions?
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Commensalism
Synergism/symbiosis Anatagonism/parasitism Neutralism |
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What are siderophores?
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Siderophores are iron-binding organic acids produced by microorganisms
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What is a siderophore auxotroph?
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An organism that cannot synthesize its own siderophore
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Give an example of a siderophore auxotroph.
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Microbacterium flavescens
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What is MIC?
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Minimal Inhibitory Concentration (antibiotics)
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What test is done to gauge antibiotic sensitivity?
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The Kirby-Bauer Test
Antibiotic-impregnated paper discs Zone of Inhibition (ZOI) = diameter |
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Will Microbacterium flavescens grow on blood slant agar without siderophores present?
Why? OR Why not? |
Yes. The hemoglobin in blood satifies the iron requirement.
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What are the commercially created siderophores called?
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Desferal discs
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Can you safely assume that organism that do not stimulate growth of Microbacterium flavescens don't make a siderophore?
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No, M. flavescens could have simply not been able to remove its siderophore.
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What media is both selective and differential?
How does it accomplish each of these? |
MacConkey's Agar.
Selective -- prevents growth of gram+ bacteria due to presence of crystal violet and bile salts (CV prevents growth by ___ and bile salts prevent growth by ___) Differential -- distinguishes lactose fermenting Gram- bacteria because they because pink-red in color and may be surrounded by a zone of precipitated bile |
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What is the equation to calculate the original titer?
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# colonies/
------------------------------------------------- (volume plated)*(cumulative dilution) |
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Name the 2 methods of dilution plating.
Describe the location of resulting colonies |
Dilution POUR plating - colonies in the agar
Dilution SPREAD plating - colonies on surface agar |
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What number of colonies are countable, TFTC, or TMTC?
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Countable 30-300
TFTC <30 TMTC >300 |
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The measurement of the amount of light absorbed when a beam is passed through a colored solution is called ___________.
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Colorimetry
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The measurement of light absorption by particles in suspension is called ________.
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Turbidimetry
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What 4 (FOUR) compounds were used for the Carbohydrate Fermentation tests?
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Glucose (monosaccharide)
Lactose (disaccharide) Sucrose (disaccharide) Mannitol (alcohol) |
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What is the purpose of the Durham tube?
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Trap gases that are produced by aerogenic fermenters
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Bacteria that ferment carbohydrates usually have what relationship with oxygen?
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Facultative anaerobes
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What is the purpose of the Carbohydrate fermentation test?
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Determine what sugars an organism is able to ferment by detecting a net accumulation of acids and gas (AEROGENIC organisms) or only acids (ANAEROGENIC organisms)
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What compound detects the presence of acidic fermentation?
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Phenol red
Red --> Orange-red (No reaction) Orange and yellow (slightly acid) Yellow (Acid) |
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For the carbohydrate fermentation test, what does the symbol of A mean?
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Acid no gas (ANAEROGENIC)
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For the carbohydrate fermentation test, what does the symbol of an A with a circle mean?
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Acid with gas (AEROGENIC)
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For the carbohydrate fermentation test, what does the symbol of an A with a dotted-circle mean?
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Acid with small amount of gas (AEROGENIC)
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For the carbohydrate fermentation test, what does the symbol of s/A mean?
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Slightly acidic
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For the carbohydrate fermentation test, what does the symbol of NR mean?
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No reaction
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For the carbohydrate fermentation test, what does the symbol of NR++ mean?
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Alkaline (degradation of peptone)
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What intracellular enzyme complex is detected by the Indole Test?
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Tryptophanase is detected by the Indole test
Tryptophanase degrade typ by splitting off INDOLE |
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What will detect the presence of Indole? How?
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Kovac's reagent
Indole + p-dimethyl... = Insoluble red compound Butanol -- extract and concentrate red compound -- float |
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The degradation of H2O2 in most organisms capable of good growth under aerobic conditions (aerobes) is accomplished by which enzyme?
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Catalase (a heme protein like the cytochromes)
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How can catalase activity be detected?
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Effervescence of O2 when H2O2 is added (BUBBLES)
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What will indicate a positive Motility Test?
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Red growth away from the stab line
Semisolid, soft agar 2,3,5-triphenol... color-->red (when growing bacteria present) |