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

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

• A. It turns purple
• B. It becomes colorless
• C. It stains pink
• D. It turns blue

Answer: (B)

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.

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.