Question

What structure of the bacterial cell appears to play the most important role in determining whether an organism is gram-positive? Explain!

Answer 1

The gram-positive bacterial cell has a thick layer of peptidoglycan in their cell wall. The cell wall is made up of alternate NAG (N-acetylglucosamine)and NAM (N-acetylmuramic acid) units. In Gram-positive cell walls there exists crosslinking between NAM units making it thick and strong. Another component called teichoic acid is present within the peptidoglycan layer which confers rigidity to the cell wall. Unlike Gram-negative bacteria, they lack the outer membrane, made up of lipopolysaccharides. So when alcohol is used in the decolorization step, Gram-positive cells retain its violet color from the crystal violet stain used in the first step of gram staining.