Microscopy Flashcards
Limitation of Human Eye
~0.2mm
Compound Light Microscope Structure
Illuminator casts light and varies via the diaphragm to focus through the condenser; stage holds the slide in place, and the light focuses through the objective lens, up the body tube, and through the ocular lens
Total magnification is equal to…
Ocular lens magnification x Objective lens magnification
Resolution
The ability of the lenses to distinguish between two adjacent objects; shorter wavelengths provide greater resolution
Maximum Resolution of a Compound Light Microscope
0.2um
When to use an oil-immersion lens?
When using magnifications greater than 400X
Brightfield/Light Microscopy
Used for fixed, stained, dead samples
Darkfield Microscopy
Used for live specimens
Phase Contrast Microscopy
Used for live specimens; converts differences in refractive indexes into contrast
Fluorescence Microscopy
Compound absorbs UV light and fluoresces with visible light
Confocal Microscopy
Used for producing 3D images
Simple Stain
Dry cells, heat, and pour stain over; e.g. methylene blue and safrinin
Differential Stain
Separates bacteria into groups
- Gram: positive (purple) or negative (pink); positive are sensitive to penicillins and cephalosporins; negative are resistant to antibiotics; kills the cells and distorts features
- Acid-fast: Identify mycobacteria and pathogenic nocardia; stains red
Special Stain
Targets specific structure of a microbe
- Endospore
- Capsule
- Flagella
Electron Microscope Features
100,000+ magnification, 0.2nm resolution, uses electron beam through a high vacuum and passes through electromagnet lens
