What happens to a Gram-negative cell after adding alcohol during Gram Staining?

Study for the MedCa Lab Assistant Test. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

When alcohol is applied during the Gram staining process, it acts as a decolorizing agent. In Gram-negative bacteria, which have a thin peptidoglycan layer surrounded by an outer membrane, the alcohol disrupts this outer membrane and causes the peptidoglycan layer to become more permeable. As a result, the crystal violet stain, which gives the initial purple color to the cells, is washed out. This loss of color means that the Gram-negative cells will become colorless at this stage of the staining procedure.

Following this decolorization step, a counterstain, usually safranin, is applied. This results in Gram-negative bacteria eventually taking on a pink color. However, the question specifically pertains to the immediate effect of the alcohol step, which is to render the Gram-negative bacteria colorless. Thus, the correct outcome after adding alcohol is that the cells become colorless.

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