Long description

This diagram shows the differences in cell wall structure between Gram-positive and Gram-negative bacteria. In the Gram-positive bacteria in (a) the peptidoglycan is a thick external layer shown in brown, while in the Gram-negative bacteria in (b) the peptidoglycan layer is much thinner and is surrounded by an outer membrane of lipopolysaccharide and protein (as a green wavy line). The inner membrane in (a) and (b) (shown as a double green line) is separated from the peptidoglycan layer by the periplasmic space.