ch.2 stuff Flashcards
Types of compound light microscopy
Brightfield
Darkfield
Phase contrast
Resolution
Ability of lenses to distinguish 2 points
What’s immersion oil used for?
To keep light from refracting
Brightfield Illumination
Dark objects visible against light background
Light reflected off specimen does not enter objective lense
Darkfield Illumination
Light objects visible against dark bakground
Opaque disk placed in condenser
Only light reflected off specimen enters objective lense
Phase Contrast
Allows us to see living organisms and internal cell structures
Brings together 2 sets of light rays, direct rays, and diffracted rays
Staining
Coloring of microorganisms with dye
Smear
Thin layer of material spread over a slide
Fixed
When microorganisms attach to the slide using head, which kills the microorganisms
In basic dyes , chromophore is ?
Cation
In acidic dyes, chromophore is?
Anion
What is negative staining?
Staining the background instead of the cell
What is a simple stain?
Use of a basic dye
What do simple stains do?
Highlight entire microorganism to visualize cell shapes and structures
What is a mordant used for?
Is used to hold/ intensify the stain
What are the most common used differential stains?
Gram Stain
Acid Fast Stain
Gram Staining steps
Apply crystal violet (purple dye)
Apply iodine (mordant)
Alcohol wash (decolorization)
Apply safranin (Counterstain)
What color is gram negative?
Pink
What color is gram positive?
Purple
What do acid fast stains bind to?
To bacteria that have waxy material in their cell walls, which are not decolorized by acid alcohol
True or false: Mycobacterium and Nocardia keep their primary dye Carbolfuschin despite decolorization of acid alcohol?
True
