Question

Gram stain : 1. Those that take up the gram stain are Gram positive 2. Those that do not are called Gram negative bacteria Regarding 1 and 2 :

Answer 1

The gram staining helps to differentiate bacteria in accordance to their physical and chemical properties of the cell wall (presence of peptidogylcan ).

PROCEDURE OF GRAM STAINING :

1. fixation of organisms on the slide by either heating or methanol fixation.

2.Primary stain is applied . Crystal violet stains all cells blue/purple

3. iodine as a mordant is then added which turns all the cells blue.

4. Decolorization with the application of  organic solvent such as acetone or ethanol, extracts the blue dye complex from gram negative bacteria and makes them colorless . however the gram positive bacteria remains blue.

this step distinguishes gram-positive from gram-negative cells.

5. The red dye safranin then stains the decolorized gram-negative cells red/pink; the gram-positive bacteria remain blue.

Gram positive bacteria are those which take up the gram stain.

Gram negative bacteria are those which do not take up the gram stain.