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38 Cards in this Set
- Front
- Back
Resolution
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The shortest distance between two points in a microscope's field of view that can be distinguished.
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Parfocal
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When moving from a lower to a higher magnification, the image of the specimen is close to being in focus.
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Total magnification
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Magnification by objective lens x magnification of the ocular lens.
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Hanging drop
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Drop of water and broth are placed on a cover slip which is then placed on a depression slide with a Vaseline surrounded depression.
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Wet mount
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A drop of water is added to the slide. Bacteria is then inoculated into drop of water. The edge of the cover slip on the slide touching the edge of the water. Cover slip is slowly lowered to prevent the formation of air bubbles.
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Simple staining
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Heat fix smear. Add stain for 1 minute. Rinse with water. Add iodine for 1 minute. Rinse with water. Blot dry.
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Negative staining
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Inoculate slide with drop of bacteria. Add a drop of Nigrosin. Use the edge of another slide to drag the dye across the slide. Let air dry and heat fix.
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Gram staining
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Inoculate slide and let air dry. Heat fix. Apply crystal violet for one minute. Rinse with water. Apply iodine for 1 minute. Rinse with alcohol. Rinse with water. Apply Safranin for 1 minute. Rinse with water and blot dry.
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Acid–fast procedure
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Inoculate slide and air dry. Heat fix. Apply Carbolfuchsin for 3 minutes. Rinse with water. Rinse with alcohol. Rinse with water. Add methylene blue for one minute. Rinse with water and air dry.
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Endospore stain procedure
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Inoculate slide and air dry. Heat fix. Apply Malachite Green on napkin on slide. Leave over steam bath for 15 minutes. Remove napkin. rinse with water. Apply safranin for 2 minutes. Rinse slide and blot dry.
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Capsule stain procedure
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Add a drop of Congo red stain to the slide. inoculate Congo red with bacteria. Take a second slide, place the edge against the drop and slide back over slide. Air dry. Cover with Maneval's satin for a minute. Rinse with water.
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Broth Characteristics |
Turbidity, pigmentation of organism, pellicle, flocullant, sediment, smell |
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Turbidity |
Cloudy growth in the broth |
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Pellicle |
floating layer of particles at top of broth |
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Flocullant |
Small masses floating around in broth |
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Sediment |
layer of particles concentrated at the bottom of the broth |
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Before starting any work with microorganisms, what is the one thing that needs to be done?
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Decontaminate the work station using disinfectant
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How long should a inoculating loop or needle be heated?
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Until it is glowing red (without making it red hot)
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Which inoculating instrument is used for a stab culture?
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A inoculating needle
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Why is it necessary to incubate plates face down?
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To prevent the build up of condensation
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Where should petri plates be labeled?
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The bottom
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Describe 5 essential actions to aseptic technique when transferring a broth culture to another broth?
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1) Cap is removed from sterile broth and tube of mouth is flamed
2) Cooled loop is inserted into the broth 3) Loop is removed from broth and tube mouth is flamed 4) Tube is closed with its lid 5) Loop is flamed and ready to use again |
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Describe 5 actions essential to aseptic techniques when transferring culture from plate to a slant?
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1) Inoculating loop is heated until red hot
2) Raise the lid of the petri plate just enough to access a colony to pick up a loopful of organisms 3) After flaming the mouth of a sterile slant, streak its surface 4) Flame the mouth of the tube and recap the tube 5) Flame the inoculating loop and return to receptacle |
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One reason for preparing streak-plate? |
To isolate pure colonies |
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Principle behind Simple/Basic stain |
Because the dye is positively charged it binds to the negatively charged bacteria staining it. |
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Principle behind Negative/Acidic stain |
Because the dye is negatively charged, it is repelled by the negative cell surface. this allows slide to be stained but not the bacteria. Bacteria is then visible against background. |
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Principle behind making a smear and fixing it |
To prevent the sample from being lost during the staining procedure. |
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Principle behind Gram staining |
Because gram negative cells have thin peptidoglycan, ethanol washes away CV-I. Because gram positive cells have thick peptidoglycan walls, the CV-I is trapped in the cell. |
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Principle behind Acid-fast staining |
Because acid fast cells contain mycolic acid, when the dye is washed away with acid alcohol, cells do not decolorize. |
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Principle behind endospore stain |
Malachite green dye is heated because endospores are dye resistant. heating acts as a mordant. Safranin is used to colorize vegetative cells. |
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Principle behind flagella stain |
Because flagella is thin, flagella stain contains a mordant which allows dye to be piled on flagella making it more visible. |
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Principle behind Capsule staining |
Because the capsule has a negative charge, a positive dye is added to stain the background. A negative dye is used to stain the cell wall, but leaves the capsule unstained and visible against the background. |
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PEA (Phenylethyl Alcohol) Agar |
Selective: Inhibits growth of gram negative bacteria. |
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EMB (Eosin Methylene Blue) Agar |
Selective: Inhibits growth of gram positive bacteria. Differential: Turns green when lactose is produced. |
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MSA (Mannitol Salt Agar) |
Selective: High tolerating bacteria grow. Differential: Turns yellow if bacteria can ferment mannitol. |
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BAP (Blood agar plate) |
Differential: Alpha hemolysis turns green, beta hemolysis turns clear, Gamma hemolysis has no clearing. |
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MAC (MacConkey Agar) |
Selective: Inhibits growth of gram positive bacteria. Differential: Lactose fermentation turns it pink. |
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Hektoen Enteric Agar |
Selective: Inhibit growth of gram positive bacteria. Differential: Fermenting colonies turn yellowish color. Non-fermenting colonies turn blue-green. Colonies that turn sulfur into hydrogen sulfide turn black. |