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17 Cards in this Set
- Front
- Back
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What is the definition of pure culture? |
It is a laboratory culture that contains only a single species of organism |
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Why should plates be inverted (lid-down) during incubation? |
To prevent the build up of condensation and allowing it to seep into the culture |
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What is the point of streaking a culture out onto a plate? |
To produce isolated colonies of an organism on a agar plate |
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What is the primary stain used in a gram stain? |
Crystal violet |
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You are given a smear of unknown bacteriaand asked to do a gram stain. If you examine your slide under the microscopeafter rinsing off the primary stain, what color would a gram-positive specimenbe at this step?
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Purple |
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You are given a smear ofunknown bacteria and asked to do a gram stain. If you examine your slideunder the microscope after rinsing off the primary stain, what color would agram-negative specimen be at this step?
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Purple |
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You are given a smear of unknown bacteria and asked to do a gram stain. If you examine your slide under the microscope after rinsing off the mordant with water, what color would a gram-negative specimen be at this step?
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Purple |
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You are given a smear of unknown bacteria and asked to do a gram stain. If you examine your slide under the microscope after rinsing off the mordant with water, what color would a gram-positive specimen be at this step?
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Purple |
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What is the name of the mordant used in a gramstain?
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Iodine |
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What is the name of the decolorizing agent usedin a gram stain?
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Alcohol |
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What is the name of the counterstain used in agram stain?
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Safranin |
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You are given a smear of unknown bacteria and asked to do a gram stain. If you examine your slide under the microscope after applying the decolorizer, what color would a gram-positive specimen be at this step?
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Purple |
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You are given a smear of unknown bacteria and asked to do a gram stain. If you examine your slide under the microscope after applying the decolorizer, what color would a gram-negative specimen be at this step?
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Colorless |
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You are given a smear of unknown bacteria and asked to do a gram stain. If you examine your slide under the microscope after applying the counterstain, what color would a gram-positive specimen be at this step?
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Purple |
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You are given a smear of unknown bacteria and asked to do a gram stain. If you examine your slide under the microscope after applying the counterstain, what color would a gram-negative specimen be at this step?
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Pink to red |
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Describe two differences between the cell walls of gram-negative and gram-positive bacteria.
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Gram-positive bacteria cell wall have a much thicker peptidoglycan layer with techoic acid. Gram-negative bacteria cell wall have a thinner peptidoglycan layer without techoic acid. Gram-negative cell wall contains a lipopolysaccharide (LPS) layer, which does not exist in the Gram-positive cell wall |
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What is the function of the mordant used in the gram-stain?
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Used to chemically change the shape of the dye molecule and trap it into the cell wall |
