Question

what are the different cell wall formations that bacteria can have? how does this affect the staining of the cells?

Answer 1

Ans:-

1. There are two main types of bacterial cell wall formation, those of gram-negative bacteria and those of gram-positive bacteria, which are differentiated by their gram staining characteristics. For both these types of bacteria, particles of approximately 2 nm can pass through the peptidoglycan.
2. The names originate from the reaction of cells to the Gram stain, a test long-employed for the classification of bacterial species.
3. Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan & teichoic acids.In contrast, gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides & lipoproteins.
4. Gram-positive cell walls are thick & the peptidoglycan (also known as murein) layer constitutes almost 95 percent of the cell wall in some gram-positive bacteria & a little as 5-10 percent of the cell wall in gram-negative bacteria.
5. The gram-positive bacteria take up the crystal violet dye & are stained purple.
6. Gram-negative cell walls contain a second plasma membrane superficial to their thin peptidoglycan layer, in turn adjacent to the cytoplasmic membrane.
7. Gram-negative bacteria are stained as pink colour.
8. A new method is given to stain bacterial cell walls ,especially of Escherichia coli & Bacillus cereus. The cells are smeared in water on a slide & as soon as air-dry ,are stained 3-4 minutes with a 1percent aqueous solution of new fuchsin.
9. Gram staining is a common technique used to differentiate two large groups of bacteria based on their different cell wall constituents.
10. Gram-positive bacteria stain violet due to the presence of a thick layer of peptidoglycan in their cell walls, which retains the crystal violets these cells are stained with.
11. In the Gram stain, a gram-negative bacterial will stain red or pink because the rinse took out the primary dye & the safrinin(secondary dye) took over the colouring as the coucter-stain.
12. The purpose of staining bacteria is to see, for example , how thick of a layer of peptidoglycan their cell wall has.
13. As explained above, the different cell wall formations in bacteria &how this affect the staining of the cells.