Most of the gram positive cell wall contain considerable amount of teichoic acid and teichuronic acid. In addition, they may contain polysaccharide molecules. The gram negative cell wall contains three components that lie outside the peptidoglycan layer:
1. Lipoprotein
2. Outer membrane and
3. Lipopolysaccharide.
Thus the different results in the gram stain are due to differences in the structure and composition of the cell wall.
