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22 Cards in this Set
- Front
- Back
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Simple Staining Technique |
a basic cationic dye is flooded across a sample adding color the cells |
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Cation |
a positively charged ion |
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Why is the background clear in a simple stain? |
because the cytoplasm in the cell walls has a negative charge and is attracted to the positively charged dye which causes just the cells/bacteria to stain |
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Is a simple stain heat fixed? |
Yes because it kills the bacteria and attaches it to the slide and enhances the stain uptake |
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Negative Staining Technique |
an acidic, anionic dye mixed with a cell sample the dye changes the color of the background not the cells causing the cells to stand out |
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Anion |
a negatively charged ion |
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Why is the negative stain background not clear? |
because the negatively charged dye with the negative charged cells, they repell off of each other and causes the background to stain and the cells to remain clear |
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What is the simple staining technique used for? |
determines cell morphology, size, and arrangement |
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Why doesnt a negative stain require heat fixing? |
So the cells are not subjected to the distorting effects of chemicals and heat their natural size and shape can be seen |
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Reagent in a gram stain |
primary stain (crystal violet)- mordant (gram's iodine)- decolorizing agent (ethyl alcohol, 95%)- counterstain (safranin) |
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Cocci shape |
sphere bacteria |
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Bacilli shape |
rod shaped |
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Cocci possibility shapes |
diplococcus=pair streptococcus=chain staphylococcus=clusters tetrad=packet of 4 sarcina=packet of 8 |
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Bacilli possibility shape |
diplobacillus=pair streptobacillus=chain |
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Gram Stain |
differentiates between a gram positive and gram negative |
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Gram Positive |
has a thick layer of peptidoglycan |
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Gram Negative |
has a thin layer of peptidoglycan |
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Gram Positive stain process |
Primary- purple Mordant-purple Decolorizing agent-purple Counterstain-pruple |
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Gram Negative stain process |
Primary-purple Mordant-pruple Decolorizing agent-colorless Counterstain-pink |
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Hanging Drop |
culture on the depression slide and put the coverslip on top of the culture drop |
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Wet Mount |
has a thin layer of petroleum jelly on the cover slip place the culture in the center of the depression slide and cover the culture with the cover slip to form a seal between the two |
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Difference between the hanging drop and a wet mount |
hanging drop lives longer than wet mount because of the petroleum jelly and because it has more of an oxygen flow then a wet mount does which seals the oxygen out |
