Gram staining differentiates between two kinds of what?

Gram staining differentiates between two kinds of what?

• A. Distinguishes two kinds of bacterial cell walls
• B. Identifies bacterial species
• C. Measures bacterial size
• D. Detects viruses

Answer: (A)

Gram staining tests how the bacterial cell wall interacts with dyes, distinguishing two kinds of cell wall structure. Bacteria with thick peptidoglycan layers retain the crystal violet-iodine complex and stay purple after the final step, while bacteria with thinner peptidoglycan and an outer membrane lose the violet during decolorization and take up the counterstain, appearing pink. This difference in wall composition is what the stain reveals, separating bacteria into Gram-positive and Gram-negative groups. This technique doesn’t identify species, measure cell size, or detect viruses, since those aspects aren’t defined by how the cell wall binds these dyes.

Gram staining tests how the bacterial cell wall interacts with dyes, distinguishing two kinds of cell wall structure. Bacteria with thick peptidoglycan layers retain the crystal violet-iodine complex and stay purple after the final step, while bacteria with thinner peptidoglycan and an outer membrane lose the violet during decolorization and take up the counterstain, appearing pink. This difference in wall composition is what the stain reveals, separating bacteria into Gram-positive and Gram-negative groups.

This technique doesn’t identify species, measure cell size, or detect viruses, since those aspects aren’t defined by how the cell wall binds these dyes.