Ch 2 Types Of Microscopy & Ex Flashcards
Source of illumination for
bright field
White light
Source of illumination for
Darkfield
White light
background is dark image is going to be light
Source of illumination for
Phase contrast
White light
Source of illumination for
TEM
Electron beams
Source of illumination for
SEM
Electron beams
Source of illumination for
Fluorescence
UV
What does TEM stand for
Transmission Electron Microscopy
What does SEM stand for
Scanning electron microscopy
Advantages of
Bright field
Can be used for both live unstained material and preserved stained material
Forms it’s image when light is transmitted through the specimen
lightweight
cheap and easy to use about $2500
living cells
Disadvantages of
Brightfield
Bacteria must be stained before we observe
Does not allow for us to observe live and interacting cells
poorest resolution 0.2 microns
low contrast: has to have color or have to stain
Advantages of
Darkfield
Visualize living cells that would be distorted by drying or heat or that cannot be stained with the usual methods
Cells do not have to be stained
better contrast than brightfield
can see live bacteria that moves like corkscrews
diagnostic tool for certain bacteria (syphilis)
easy to use
living cells
Disadvantages of
Darkfield
Cannot see color
Distorts size
surface area can get distorted (glare) (topography)
cannot use for stained stuff because it can lead to more distortion
light can kill or damage sample
Advantages of
Phase Contrast
Observing intracellular structures such as bacterial endospores, granules, and organelles, as well as the locomotor structure of eukaryotic cells such as cilia
can see live cells
can kind of see 3D imagery in the sample
about 5k-7k
living cells
Disadvantages of
Phase Contrast
Decreased resolution
Thick specimens appear distorted has a halo effect
Advantages of
TEM
views detailed structure of cells and viruses (inside)
can reach 100,000x TM
can see inside (intracellular detail)
2.5 nm (resolution
dead cells
Disadvantages of
TEM
can see dead speciamens
operation and analysis requires special training
very expensive
$1 million
have to provide the contrast
have to coat the sample with something sometimes gold
always in black and white
coat in heavy metal
inability to view live samples
Advantages of
Bright field
Can be used for both live unstained material and preserved stained material
Forms its image when light is transmitted through the specimen
lightweight
cheap and easy to use about $2500
dead cells
Advantages of
SEM
creates an extremely detailed 3-dimensional view of all kinds of objects, from plaque on teeth to tapeworm heads
modern SEMs allow for the generation of data in digital form
can see outside (extracelllular detail)
scan the surface
dramatic and realistic images
10,000x TM
resolution: 20 nanometers
can view viruses (outside)
Disadvantages of
SEM
limited to solid samples
special training is required
expensive
coat with gold and platinum
hard to access
images in black and white
inability to analyze live specimens
Advantages of
Fluorscence
diagnoses infections and pinpointing particular cellular structures
more accurate
better resolution
stain (antibody) to see if what is in the infection on the antigens
good for research
immunology
about $200k
dead cells
Disadvantages of
Fluorescence
higher cost
technical complexity
if you do not have a stain it will not be useful
most of the time samples are dead
can use on living samples if they naturally fluorescence
has to be pitch black
