When performing GRAM STAIN, explain a. What would happen if you let the alcohol rinse (decolorizing...

When performing GRAM STAIN, explain

a. What would happen if you let the alcohol rinse (decolorizing step) for too long? What is the correct term to describe this?

b. What would happen if you reversed the order of the mordant and the primary stain?

c. Fill out this chart ****

STEP	REAGENT	PURPOSE (FUNCTION)	GM+ Color	GM- Color
1
2
3
4

Solutions

Expert Solution

Answer- a: the alcohol rinsing or decolorising step should not be performed for more than 5 seconds , because otherwise this would cause the leaching out of crystal violet- iodine complex from the pores of gram positive bacteria due to dissolution of lipid layer. As a result, gram positive bacteria would also take up safranine dye just like gram negative bacteria and both types of bacteria would appear pink.

Answer-b: the purpose of using mordant (iodine) is to make a huge complex of crystal violet and iodine which fits inside the pores of thick peptidoglycan layer of gram positive bacteria. This complex is big enough that it cannot leach out easily during the decolorizing step.

However, according to the question, if the mordant and primary staining step is reversed then gram positive bacteria will not take up violet color because mordant iodine would have nothing to bind with it in order to form a complex.

gladiator answered 1 year ago

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