Gran Staining

Question 1

Gram positive bacterial cells

Answer 1

Thick peptidoglycan layer
Outer lypopysacharaide layer
Not destroyed by penicillin

Question 2

Gram negative cells

Answer 2

Thin peptidoglycan layer
No lypopolysacharide layer
Destroyed by penicillin

Question 3

Gram staining method ?

Answer 3

Place sample on slide with heat flame to fix it
Add crystal violet dye to the sample turning all the cells purple
Then add iodine to help the crystal violet dye strongly bind to the gram positive cells
Then add a secondary dye , safranin which turn all gram negative cells pink
Then add a deco colourising agent to wash away any iodine and crystal violet dye still bonded to gram negative cells