In Gram staining, which group appears purple after the staining procedure?

In Gram staining, which group appears purple after the staining procedure?

• A. Gram-negative pink
• B. Gram-positive purple
• C. Gram-variable
• D. Acid-fast

Answer: (B)

Grams staining differentiates bacteria by cell wall structure. The crucial point is that Gram-positive organisms have a thick peptidoglycan layer that traps the crystal violet-iodine complex and holds onto it during the decolorization step, so these cells stay purple when the counterstain is applied. In contrast, Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, which allows the decolorizer to wash out the primary stain, so they take up the pink counterstain. Acid-fast organisms require a different stain approach, and Gram-variable results can occur under certain conditions. Therefore, the group that appears purple after the staining procedure is the Gram-positive bacteria.

Grams staining differentiates bacteria by cell wall structure. The crucial point is that Gram-positive organisms have a thick peptidoglycan layer that traps the crystal violet-iodine complex and holds onto it during the decolorization step, so these cells stay purple when the counterstain is applied. In contrast, Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, which allows the decolorizer to wash out the primary stain, so they take up the pink counterstain. Acid-fast organisms require a different stain approach, and Gram-variable results can occur under certain conditions. Therefore, the group that appears purple after the staining procedure is the Gram-positive bacteria.