The Gram positive bacterial cell wall is made up of thick peptidoglycan layer which is rich in Teichoic acids. These teichoic acids are negatively charged because of presence of phosphate in their structure.
The Gram negative bacteria have an outer membrane composed of phospholipids and Lipopolysaccharides. The lipopolysaccharides impart a strongly negative charge to surface of Gram negative bacterial cells.
Wiki User
∙ 12y agoBecause Nigrosin is an acidic dye--carries a negative charge--and repels against the negatively charged cell walls of most bacteria.
basic dyes are more effective for bacterial staining than acidic dyes because basic dyes have a positive charged chromogen. Bacterial nucleic acids and certain cell wall components carry a negative charge that strongly binds to the cationic chromogen.
cell walls
In the gram staining process, gram positive bacteria appear to be purple because their cell walls, which contain a large concentration of peptidoglycans, are strongly dyed. Gram negative bacteria appear pink because their walls asborb less dye. This occurs becayse there is a smaller concentration of peptidoglycans and an additional lipid layer surrounds the cell wall. ANSWER The exact mechanism of action of this staining technique is not clearly understood. However, it is known that differences in the biochemical composition of bacterial cell walls parallel differences in their Gram-stain reactions. Gram-positive bacterial walls are rich in tightly linked peptidoglycans (protein-sugar complexes) that enable cells to resist decolorization. Gram-negative bacterial walls have a high concentration of lipids (fats) that dissolve in the decolorizer (alcohol, acetone, or a mixture of these) and are washed away with the crystal violet. The decolorizer thus prepares gram-negative organisms for the counterstain.
Mycobacterium
Because Nigrosin is an acidic dye--carries a negative charge--and repels against the negatively charged cell walls of most bacteria.
The effect on the bacteria depends if the stain is an acidic or basic stain. Most bacteria are stained when a basic stain permeates the cell wall and adheres by weak ionic bonds to the bacterial cell, which is slightly negatively charged.
only plant and bacterial cells have walls
basic dyes are more effective for bacterial staining than acidic dyes because basic dyes have a positive charged chromogen. Bacterial nucleic acids and certain cell wall components carry a negative charge that strongly binds to the cationic chromogen.
cells
As far as I'm aware - no. Chitin is present in the cell walls of funghi but I believe bacterial cell walls are mostly made of proteoglycans.
In the gram staining process, gram positive bacteria appear to be purple because their cell walls, which contain a large concentration of peptidoglycans, are strongly dyed. Gram negative bacteria appear pink because their walls asborb less dye. This occurs becayse there is a smaller concentration of peptidoglycans and an additional lipid layer surrounds the cell wall. ANSWER The exact mechanism of action of this staining technique is not clearly understood. However, it is known that differences in the biochemical composition of bacterial cell walls parallel differences in their Gram-stain reactions. Gram-positive bacterial walls are rich in tightly linked peptidoglycans (protein-sugar complexes) that enable cells to resist decolorization. Gram-negative bacterial walls have a high concentration of lipids (fats) that dissolve in the decolorizer (alcohol, acetone, or a mixture of these) and are washed away with the crystal violet. The decolorizer thus prepares gram-negative organisms for the counterstain.
cell walls
cell walls protect the plant from bacterial invasion
Vaccine
Mycobacterium
chitin