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8 Cards in this Set
- Front
- Back
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Four reagent types of the Gram test
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1. Primary stain
2. Mordant 3. Decolorizer 4. Counterstain |
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Actual chemicals in the Gram tests
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1. Crystal violet
2. Gram's iodine 3. Acetone-alcohol 4. Safranin |
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Positive Result for Grahm's
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Purple or blue. Basically, the Primary Stain did not wash off and remains. So whatever the primary stain's color is determines what the end result color is.
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Negative result for Grahm's
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Red or Pink. Primary Stain did wash off, and Safranin, the counter stain, had room to connect to the cell walls.
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Interval between chemical applications
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Generally one minute
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Procedure for Grahm Stain
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1. Smear a loopful on slide
2. Let dry 3. heat fix the slide 4. apply primary stain, wash in water 5. apply mordant, wash in water 6. apply decolorizer, wash in water 7. apply counterstain, wash with water 8. let dry, then examine under microscope 8. |
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Cell Wall constituents that yield a GRAM + reaction
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-Multiple peptidoglycan layers
-teichoic acids -Polysaccharides |
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Cell Wall constituents that yield a GRAM - reaction
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-Single peptidoglycan layer
-Phospholipids -Lipoproteins |
