Resolution of different types of microscopy stains vs

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Resolution of different types of microscopy Stains vs. optical contrast Immunofluorescence vs. GFP Living vs. dead cells What is it possible to see with various techniques?
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Counting bacteria -are they growing? -how many are we using in this experiment? -how many are present in a diseased sample? 1) Direct microscopic count
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2) Viable count or colony count Counts number of cells in a sample capable of growing up into a colony on solid medium. ONLY living cells are counted Advantages: – different colony morphologies can be observed on plates Disadvantages: – if you are counting cells from an environmental sample, the medium may be suitable for one species but not for others – could take days/weeks for colonies to grow
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3) Turbidity -indirect measurement of bacterial numbers As bacteria in grow, they convert nutrients into cell mass. Cultures appear turbid or opaque because light passing through the sample is scattered by bacteria. The turbidity of a culture (its optical density ) is proportional to the number of cells present.
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Turbidity or optical density is proportional to cell number, but the exact relationship is different for each species due to cell size and shape. You must generate a standard curve that relates OD to cell number counted by an independent method, such as a direct microscopic count. Advantages: rapid no sample destroyed Disadvantages: does not distinguish between live and dead cells does not distinguish between different kinds of cells
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