Gram Staining Flashcards
Bacterial smear
The transfer of microorganisms onto a slide that can subsequently be stained
What 3 goals does heat-fixing a slide achieve?
Adheres bacteria to slide surface
kills most microorganisms without destroying structural features
enables many stains to better penetrate/react with the microorganisms
Why is it important to dry the slide before heat fixing it?
The presence of liquid will boil the microorganisms and destroy structural features
What is the primary stain?
Crystal violet
What is the counter stain?
Safranin
What is the mordant?
What does a mordant do?
Iodine
Supports the primary stain’s retention in gram-positive cells
What is the decolorizer?
What does a decolorizer do?
Ethanol/Ethyl
Helps gram-positive cell walls retain the primary stain, while removing it from gram-negative outer membranes
Does safranin only stain gram-negative cells?
No- it stains both, but the crystal violet retained in gram-positive cells masks it
