Microbio – Microbiology Answers – Flashcards
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Solution |
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a homogeneous mixture of two or more substances, which may be solids,liquids,gases,or a combination of these. |
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Solute |
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a substance dissolved in another substance, usually the component of a solution present in the lesser amount |
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Solvent |
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liquid,capable of dissolving another substance |
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chromophore |
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the colored solute in a solution |
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Stains |
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Stains are solutions that contain a solvent and a colored solute called a chromophore |
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Methylene Blue |
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blue, sometimes a blue-green color |
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Crystal Violet |
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blue-purple |
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Safranin |
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purple-red |
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staining helps determine |
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cell morphology, size and arrangement |
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gram staining uses 2 basic stains |
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crystal violet and Safranin |
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Gram Stain |
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purpose to distingguisg between gram positive ans gram- negative bacteria |
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gram stain steps |
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1 flood mear with crystal violet (60 sec) 2 rinse with water 3 flood the smear with iodine (at least 1 min) 4 rinse again with water 5 decolonize with alcohol until fluid runs clear (no longer than 30seconds) 6 rinse again with water 7 counter stain with safranin (60 sec) 8 rinse again with water 9 Blot dry |
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basic stains have a positively charged chromophore which forms an ionic bond with the negatively charged bacterial cell. |
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Gram- positive cells have the ability to resist alcohol decolorization |
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gram+cells have lower lipid content in their cell walls. |
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safranin is used as to counterstain gram- negative cells |
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decolotization with ethanol removes crystal violet |
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