Gram Staining
-- invented by Hans Christian Gram in 1884
-- helped distinguish groups of bacteria
-- identifies cells based on their ability to absorb certain dyes
-- gram-positive = cell does not remove the dye
-- gram-negative = cell does not hold dye, and is stained with a counterstain
-- cell walls that absorb the dye are made of peptidoglycans
-- alcohol does not remove this dye
-- lipopolysaccharides do not hold the dye
-- these are bleached with alcohol easily
-- gram-negative examples -- pseudomonas -- legionella -- hemophilus
-- gram-positive examples -- staphylococcus -- clostridium -- listeria
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