Chapter 4 Microscopy, Staining, and Classification Flashcards
Principles of Microscopy (4)
1 wavelength
2 magnification
3 resolution
4 contrast
Wavelength
length between 2 crests of light
visible light spectrum
(purple, short) 400nm - 700nm (red, long)
Magnification
process of enlarging something in appearance
Resolution
how close 2 points in the image can be before they are no longer seen as 2 separate points
clarity of an image
Contrast
difference of intensity bw 2 objects or an object and its background
Simple Bright-Field Microscope
- light microscopy
- single magnifying lens
- similar to magnifying glass
- leeuwenhoek used simple microscope
Compound Bright-Field Microscope
- light microscopy
- series of lenses for magnification
- light passes thru specimen into objective lens
- oil immersion lens increases lenses
- 1 or 2 ocular lenses
- may have condenser lights
Total Magnification
(objective lens)x(ocular lens)
Dark-Field Microscopes
- light microscopy
- best for observing pale/unstained objects
- only light rays scattered by specimen enter the objective lens
- specimen appears light against dark background
- increases contrasts and enables observation of more details
- ideal for visualizing spirochetes
Electron Microscope
- greater resolving power and magnification
- 10,000x to 100,000x
- detailed view of bacteria, viruses, ultrastructure, and large atoms
Light Microscopes
-cannot resolve images closer than 200nm
2 types: bright-field and dark-field
2 types of Electron Microscopes
1 Transmission Electron Microscopes (TEM)
2 Scanning Electron Microscopes (SEM)
Transmission Electron Microscopes (TEM)
- 2D images
- cross sectional
Scanning Electron Microscopes (SEM)
- 3D images
- topographies