Topic 2 - Microscopy Flashcards
Magnification
How much bigger an object is that the original
Resolution
How far apart 2 points can be before theyre seen as one
Types of microscopes
4
- optical
- transmission electron
- scanning electron
- ultra structure
Types of microscopes
Optical
- beam of electron through object
- objective lens + eye piece magnify sample
mag = 1500x res =200nm
Types of microscopes
transmission electron
-beam of electrons through sample / 2d image
-thin sample used
mag = 50,000x res=0.1nm
Types of microscopes
Scanning electron
- beam of electrons back and forth over surface of object / 3D
mag= 50,000x res=0.1nm
Types of microscopes
Ultra structure
structures only visible through TEM
- electron microscopes show more due to their shorter wavelengths, giving higher resolution
Types of microscopes
why is staining required for samples
- provides contrast btwn organelles and cytoplasm
- allowing structures to be observed
Types of microscopes
what type of stain used for electron microscopes and why?
-heavy metals
- electrons to reflect
Types of microscopes
what stain is used for light microscopes?
- methylene blue
- acetocarmine
- haematoxylin
1 advantage of electron microscopes
- higher resolution and magnification
3 disadvantages to electron microscopes
- very expesive + not portable
- sample must be placed in vacuum, can’t magnify living things
- produces only black and white images
