QUIZ D – Flashcards
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Describe briefly the purpose of performing a Standard Plate Count in a microbiology laboratory
answer
In order to estimate an unknown bacterial cell concentration
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Suppose your professor handed you a test tube of an unknown concentration of E. coli broth culture and told you to make a 10-2 dilution of the culture. Explain how you would do this
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Make a 1 to 100 dilution. Put 10 ul of the broth into 990 ul water or saline
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Plating 0.1 ml of a sample diluted by a factor of 10-3 produced 43 colonies. What was the original concentration in the sample
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OCD=43/10^-4= 43 x 10^4 or 4.3 x 10^5
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Write the formula for calculating original density (OCD)
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OCD= CFU/FDFxV
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Why would you not plate an E. coli culture directly with a cell density of 2 x 1010 cells in order to count?
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Would be too numerous to count on the plate
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What units do you typically report OCD in?
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CFU/ml
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Name the three genes contained within the pGLO plasmid?
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araC/GFP/bla
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Define bacterial transformation
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The genetic alteration of a cell resulting from the direct update of DNA from its surroundings
