Topic 3
Terms
undefined, object
copy deck
- define Microscope
- An optical system for magnification and illumination
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Light Microscopy (1000x2000x)
--Brightfeild microscope -
-used everyday in labs
-drk object on light background
-2 lens system(objective and ocular )
-Illumination-articifial light source has a condenser lens
-resolving power-wave length of light --- the smaller the better resolution
-usually stained and dead , which causes distortion
-if the MO is alive it the light has to be reduced to see the MO -
Light Microscopy (1000x2000x)
--Dark feild Microscopy -
--differs from brightfeild in that there is a special condenser that directs light away from the objective and only light that has struck the seample is reflected back to the objective and visible.
--sample is living and unstained -
Light Microscopy (1000x2000x)
Flouresence Microscopy -
specimen has been stained with a flouresent stain, this gives off visible light when bombbarded with UV light
--flouresent dyes can be atteced to antibodies to view specific species
USED TO IDENTIFY SPECIFIC SPECIES -
Light Microscopy (1000x2000x)
Phase contrast microscopy and interface microscopy -
permit contrast to be observed in diffrent parts of the cell without the use of dyes or stains
--diffrent parts of the cell have diffrent indexes and this allows diffrent shades of gray for diffretn parts of the cell
--used to view living and unstained specimens
GREAT for cilia, flagella and intercellualr oragnisms - Electron Microscopy ( 500000-1000000x)
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-electron beams have much shorter wave lengths than light visible light , This greatly improves reseolution
-lenses are made of magnets
-image viewed on a monitor -
Electron Microscopy ( 500000-1000000x)
Name 2 types -
TEM - transmission electron Microscopy
have very thin slices of samples that the electron beam passes thru
SEM-scanning electron microsope- coat the surface of the sample with platinum and the beams bounce off the sample instead of thru it, great 3D effect - disadvantage of Electron Microscopy
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-very expensive
-samples are dead killed always
-very lenghty sample preparation
-difficult to maintain the microscope
-no color - Wet mount sample or hanging drop
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-Best for viewing living organisms
-also good for viewing structures that otherwise would change when being stained
-best if used with brightfeild microscopy or dark feild microscopy
-remember to decrese the light of using brightfeild microscopy - Differential Staining
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-dried fixed and stained smears of specimens
-dried, speread specimen on slide and let air dry
-fixed- heat fix by passin g thru the flame 2 or 3 times
- causes distorion-shrimkage and change in shape
-used to identify parts of cells ex spores or flagella
Look at handout for examples - Negative staining
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-apperance similar to dark feild microscopy
-good for capsule stains
-use india ink or nigrosin
-no heat fixing thus less distortion
-similar to darkfeild we see the specimen at lighter spots
-no shrinkage