Question

right answer please

At the end of the Gram stain, gram-positive bacteria will be seen as purple cells. True False

Answer 1

The Gram stain is the most significant staining procedure in microbiology.

It is used to differentiate between gram positive organisms and gram negative organisms(bacteria).

Hence, it is a differential stain.

Gram staining involves a four-part process/method , which includes:

1-crystal violet(the primary stain)
2- iodine(the mordant- dye fixative is a substance used to set dyes)
3-a decolorizer made/manufactured from  acetone and alcohol
4-safranin(the counterstain ).

Gram negative and gram positive organisms are distinguished from one another by differences in their cell walls. These differences affect -aspects of the cell takes up and retains stains.

Principle- Just In case of gram-positive bacteria

Gram positive cells take up the crystal violet, which is then fixed in the cell with the iodine mordant.

This forms -crystal-violet iodine complex which remains in the cell even after decolorizing.

This happens because the cell walls of gram positive organisms include a thick layer of protein-sugar complexes called peptidoglycans.

This layer makes up 60-90% of the gram positive cell wall.

Decolorizing the cell causes this thick cell wall to dehydrate and shrink, which closes the pores in the cell wall and prevents the stain from exiting the cell.

At the end of the gram staining procedure, gram positive cells will be stained a purplish-blue color.

In case of gram-negative

Gram negative cells also take up crystal violet, and the iodine forms a crystal violet-iodine complex within the cells like gram positive cells.

The cell walls of gram negative organisms do not retain this complex when decolorized.

Peptidoglycans are present within the cell walls of gram negative organisms, but they only comprise 10-20% of the cell wall.

Gram negative cells also have an outer layer which gram positive organisms do not have and this layer is made up of lipids, polysaccharides, and proteins.

Exposing gram negative cells to the decolorizer dissolves the lipids in the cell walls, which allows the crystal violet-iodine complex to leach out of the cells.

This allows the cells to subsequently be stained with safranin.

At the end of the gram staining procedure, gram negative cells will be stained a reddish-pink color.

Hence according to question ,the correct option is true -at the end  of stain,gram positive bacteria will be seen as purple cells.