Question

chemical differnces between the cells walls gram positive and gram negative bacteria that may explain differnces in the rate of decolorization

Answer 1

chemical differences between the cells walls gram positive and gram negative bacteria that may explain differences in the rate of decolorisation

Answer:

Gram staining is a differential staining technique that differentiates bacteria into two groups: gram-positives and gram-negatives. The procedure is based on the ability of microorganisms to retain color of the stains used during the gram stain reaction.

Bacteria that have cell walls made up of peptidoglycan are termed gram positive. Gram positive bacteria have a thick cell wall with lots of peptidoglycan. In gram staining, the bacteria is stained with crystal violet and iodine .Then it is washed by alcohol and acetone .These bacteria retain primary stain crystal violet (The primary stain (crystal violet) binds to peptidoglycan) and are not decolorised by alcohol treatment during Gram Staining. They appear violet after staining. The result shows that this is gram positive bacteria.

  

Gram-negative bacteria have thinner inner layer of peptidoglycan cell walls, they do not form complexes with the primary stain( The bacteria did not absorb the dye) . Gram-negative bacteria are decolorized by the alcohol, losing the color of the primary stain, purple. After decolorization step, a counterstain( safranin)  is used to impart a pink color to the decolorized gram-negative organisms.