Q.Differentiate Gram positive and Gram negative bacteria.

Step 1. Cell wall thickness and layering. Gram positive bacteria have a single-layered cell wall about 0.015-0.02 um thick; Gram negative bacteria have a triple-layered wall, thinner overall at about 0.0075-0.012 um.

Step 2. Rigidity and chemical composition. The Gram positive wall is rigid, being about 80% peptidoglycan (with about 20% polysaccharide) and containing teichoic acid; it is this high peptidoglycan content that makes it rigid. The Gram negative wall is comparatively elastic, with only 3-12% peptidoglycan (the rest being polysaccharides and lipoproteins), and it lacks teichoic acid entirely.

Step 3. Outer membrane and periplasmic space. Gram positive bacteria have no outer membrane and no periplasmic space at all. Gram negative bacteria have both - a distinct outer membrane (carrying lipopolysaccharides, porins and lipoproteins) sitting outside the thin peptidoglycan layer, with a periplasmic space in between the outer membrane and the cytoplasmic membrane. …

Work through Table 1.6's ten comparison points category by category: wall structure/thickness, chemical composition, ou …

• Only listing the staining outcome (violet vs pink) instead of the underlying structural reasons. …