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17 Cards in this Set
- Front
- Back
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resolution formula?
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Resolution/2NA
NA= light gathering capacity |
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2 cationic dyes? 2 anionic dyes?
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Cationic= Meth blue or crystal violet
Anionic= Acid Fuschin, Congo Red, Nigrosin |
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What is Sudan Black dye? Indol dye?
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Fat soluble, stains granules of Poly-B-
OH butyric acid. India Ink, not water soluble. |
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What 2 dyes for Negative Stain? Why? Heat fixed?
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Nigrosin is black ionic dye repelled by - charge on cell surface. India Ink has no charge and doesn't penetrate cell. Never heat fixed- see size, shape
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Blot with simple stain? Why use 1 dye?
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Yes. Stain all cells to tell diff. shapes & sizes
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What does Iodine do in gram stain? why are Gm(+) cells purple after gram stain?
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Iodine is mordant that causes crystal violet to adhere to gm (+)'s because it is difficult with thicker peptidoglycan cell wall
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why are gm (-) cells reddish/pink?
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crystal violet-iodine complex was leached during decolorization and counterstain safranin absorbed due to thinner layer of peptidoglycan in walls
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why use steam in acid fast? used what method?
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steam forces carbol fuschin thru resistant mycolic wax content of cell walls. Ziehl-Neelsen Method
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cerease or pink violet result in acid fast stain? Blue result?
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Acid fast + cells retain dye (carbol fuschin) bcs high wax. Acid fast - cells decolorize from alcohol and counterstain blue
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acid fast genera? acid fast - microorg?
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Mycobacterium - M. tuberculosis, M. leprae. Nocardia (use less stringent decolorizer). Ecoli is acid fast -
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Red on SS agar? Colorless? Dark centers?
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Red on SS agar is Lac (+)
Colorless is Lac (-) ex: Salmonella H2S producers show dark centers |
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Dark blue or pink on EMB? White?
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Dark blue or pink on EMB is Lac (+)
White is Lac (-) |
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Bismuth Sulfite selects for?
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Salmonella
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Change from red to brilliant green on BGA? Dye remains red?
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Red to brilliant green is Lac (+)
Dye remains red is Lac (-) ex: Salmonella |
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Red on DES? Colorless?
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Lac (+) is red on DES
Colorless is Lac (-) ex: Salmonella |
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Advantage of DMC on milk?
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Shows living and dead orgs. Quickly shows Staph.
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What test differentiates Salmonella from Proteus?
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Salmonella is urease -
Proteus is urease + |
