both crystal violet and safarin are basic stains and may be used to do simple stains on Gram-positive and Gram-negative cells. This being the case, what makes the Gram stain a differential test?This being the case, what makes the Gram stain a differential test?
Gram positive bacteria have a thick covering (lipopolysaccharide) that absorbs the crystal violet, turning the bacteria purple. gram negative bacteria have a thin covering that won't allow the crystal violet to penetrate it. Safranin has to be used to stain gram negative bacteria.This being the case, what makes the Gram stain a differential test?
If by this you mean what does it differentiate between - it is to do with the strucure of the cell wall.
Gram -ve bacteria have an additional outer membrane formed with lipids, preventing the stain from colouring it.
It is a differential stain simply because it allows you to differentiate between G+ and G-.
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