Gram staining

Question 1

When cells are stained with crystal violet (primary stain), what will the state of bacteria be?

Answer 1

Cells stain purple

Question 2

When stained with iodine (mordant), what will the state of bacteria be?

Answer 2

Cells remain purple

Question 3

When stained with alcohol (decolouriser,) what will the state of bacteria be?

Answer 3

Gram positive cells remain purple, gram negative cells become colourless

Question 4

When stained with safarin (counter stain) what will the state of bacteria be?

Answer 4

Gram positive cells remain purple, gram negative cells appear red