Saran's Learn Microbiology

Difference between Gram positive bacterial cell wall and Gram negative bacterial cell wall Features Gram Positive Bacterial Cell wall Gram Negative Bacterial Cell wall Gram staining Appears in Violet colour Appears in Pink colour Thickness 15 – 18 nm 7 – 8 nm Peptidoglycan Thick (Multilayered) Thin (Single layered) Teichoic acids Present Absent Periplasmic space Absent Present Outer membrane Absent Present Lipopolysaccharides Low High Lipid & Lipoproteins Low (Only in Acid fast bacteria have lipid linked to Peptidoglycan) High (because of the presence of Outer membrane) Porins Absent Present Cell wall disruption by Lysozymes High

GRAM POSITIVE BACTERIAL CELL WALL Gram positive bacterial cell wall (Source: open.oregonstate.education) A model of the constitution of Gram positive bacterial cell wall (Source: scienceprofonline.com) ·        Cell wall is present outside the Cell membrane. ·        Cell wall acts as a backbone of cell and gives shape and rigidity to the cell. ·    Bacterial cell wall confers Osmotic protection from toxic substances and Gram staining characteristics. ·     The cell walls of almost all the bacteria is made up of Peptidoglycan, also called murein or mucopeptide cell wall. It is found only in Prokaryotes. ·      The Peptidoglycan consists of two components viz., (i) Peptide portion which is composed of Amino acids connected by Peptide linkages and (ii) Glycan or Sugar portion. ·        The Glycan portion, which forms the backbone of Peptidoglycan, is composed alternating units of amino sugars N-acetyl-glucosamine (