Gram Negative and Gram Positive Cell Walls

    Cards (6)

    • Gram Positive Bacterium Cell Wall
      • have a thick peptidoglycan layer in their cell wall
      • responsible for the characteristic purple stain due to the retention of crystal violet dye
      • the teichoic acids embedded within or linked externally to the peptidoglycan are responsible for the strength of the bacterial cell wall
    • Structure and Components of the Gram Positive Bacterium Cell Wall
      • the cell wall has a primary component called peptidoglycan, which makes up to 80-95% of the cell wall, providing its rigidity
      • techoic and lipotechoic are other major components contributing to their characteristic properties
    • Gram Negative Bacterium Cell Wall
      • encased by a thinner peptidoglycan shell, making them stain pink in a gram stain due the inability to retain crystal violet dye
      • structurally more complex, with multiple layers
    • Structure and Components of the Gram Negative Bacterium Cell Wall
      • thin peptidoglycan layer, only making up to 10% of the bacterial cell wall
      • have a outer membrane, this encompasses the peptidoglycan layer and has lipopolysaccharides and proteins imbedded within it
    • Lipopolysaccharides (LPS)
      • outer leaflet of the outer membrane is made of lipopolysaccharides (LPS), which is a strong endotoxin causing inflammatory responses
      • LSP has three parts: O-antigen, core polysaccharide and lipid-A
      • the lipid-A component triggers much of the immune response to gram negative bacterium
    • Comparison of Gram Negative and Gram Positive Cell Wall
      • the thickness of the peptidoglycan layer and the presence of an outer membrane in gram negative bacterium
      • the difference in the structure means that gram negative is typically more resistant to antibiotics than gram positive due to the extra layer that the drug needs to penetrate
      • gram negative is more likely to be pathogenic due to the immune response triggers by LPS