Scelta multipla
In the Gram stain procedure, what is the correct sequence of reagents applied to a heat-fixed bacterial smear (excluding the initial water rinse)?
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9. Microscopes
Gram Stain
Scelta multipla
Which of the following reagents is used to stain gram negative cells pink (or red) in the gram stain?
A
Iodine.
B
Safranin.
C
Crystal violet.
D
Decolorizing agent.
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Understand the Gram staining process: Gram staining is a differential staining technique that distinguishes between Gram-positive and Gram-negative bacteria based on the composition of their cell walls.
Identify the primary stain: The process begins with the application of crystal violet, which stains all cells purple.
Apply the mordant: Iodine is used as a mordant to form a complex with crystal violet, helping it adhere to the cell walls.
Use the decolorizing agent: Alcohol or acetone is used to decolorize the cells. Gram-positive cells retain the crystal violet-iodine complex, while Gram-negative cells do not.
Apply the counterstain: Safranin is used as a counterstain to color the decolorized Gram-negative cells pink or red, allowing them to be distinguished from the purple Gram-positive cells.
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