microscopy Flashcards
What is magnification?
the number of times larger an image is than the object
what is resolution?
how easy it is to distinguish between two points from each other. A higher resolution means you can see more detail
what are the 4 different types of microscope?
light microscope, laser scanning confocal, scanning electron microscope (SEM), transmition electron microscope (TEM)
how does a SEM work?
a beam of electrons is sent across the surface of the sample and are then collected.
how does a TEM work?
a beam of electrons is transmitted through sample and focused to produce an image. It has the best resolution
name the 6 parts of a light microscope
objective lens, eye piece, coarse focusing knob, fine focusing knob, stage, light
what are the identifying factors to look out for when identifying which type of microscope is being used?
SEM - the image looks 3D, there is shading and only the surface is shown
TEM - there is a very good resolution and you can see smaller organelles.
light - the resolution is not as good as a TEM and you can only see larger structures like the nucleus.
laser scanning confocal - the image looks 3D
how does a laser scanning confocal work?
the sample (which is stained with a fluorescent dye) is scanned with a laser beam, which is then reflected by the fluorescent dye. multiple depth of the sample are scanned to produce an image
compare the features of each microscope
light - cheap, easy to use, portable
laser scanning confocal - computer assembled image, high resolution, high contrast, depth control
electron microscope - beam of electrons focused by magnets, large and expensive, not easy to use
are the specimens living in each type of microscope?
light and laser scanning confocal - Yes
electron - No
compare the magnification of light microscopes compared to TEM and SEM
light - less than electron microscopes, up to x1500
SEM - x 200,000
TEM - x 2,000,000
put the different types of microscope in order of how high there resolution is (and state the range of resolution)
light & laser scanning confocal - above 200nm
SEM - 1-20nm
TEM - 0.05-1nm
what is the name for each image created by each different microscope type?
light - photomicrograph
laser scanning confocal - computer generated image
electron microscope - electron micrograph
equation for magnification
magnification = image size / real size
explain why staining is useful for light microscopy
it allows naturally transparent tissues to be viewed through electron and light microscopes, by making them visible.
