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Title: Why do some bacteria retain the Gram stain while others do not? Post by: nursing101 on Feb 5, 2013 Why do some bacteria retain the Gram stain while others do not?
and Can u identify beneficial and one harmful role of Gram-negative enteric bacteria found in the human body? Title: Why do some bacteria retain the Gram stain while others do not? Post by: smorgan6616 on Feb 5, 2013 It has to do with the cell membrane. I'll give you a hint, e-coli is a biggie.
Title: Why do some bacteria retain the Gram stain while others do not? Post by: lenazoni20 on Feb 5, 2013 Content hidden
Title: Why do some bacteria retain the Gram stain while others do not? Post by: nursing2012 on Feb 5, 2013 in a nut shell, G+ bacteria have a thicker cell wall then G- bacteria. G- bacteria has a thin cell wall with high lipid content because of an outer membrane that covers the cell wall. When you rinse the slide with 95%ethanol, the ethanol extracts the lipids, making it more porous and incapable of retaining the crystal violet-iodine complex. When the counterstain, Safranin, is added, G+ cells will become a darker purple while the G- cells stain pink.
beneficial: E. coli lives in the human GI tract to help digest food harmful: If E. coli was ingested, can cause food poisoning Title: Why do some bacteria retain the Gram stain while others do not? Post by: rixter119 on Feb 5, 2013 1. The "Gram stain" is actually a complex created by the combination of two stains: crystal violet and Gram's iodine followed by a decolorizer and counter stain Safranin. Basically, due to the chemical structure of their cell walls, purple color created by the stain complexes remains in the Gram-positive because of the many layers in the cell mambrane. Gram-negative does not keep the stain and loses its color because the cell wall is much thinner.
2. Generally, Gram-negative bacteria are more pathogenic / disease-causing (such as staph and strep as well as E. coli and Salmonella). |