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9 Cards in this Set
- Front
- Back
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Light microscopes (LMs)
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-microscopes first used by Renaissance scientists
-likely to use in laboratory -visible light passed through specimen and then through glass lenses -lenses refract (bend) light - causes image of specimen to be magnified -can't resolve details finer than 200 nanometers (0.2 um) (size of small bacterium) -magnify 1000 times the actual zise |
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magnification
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ratio of objects size to real size
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resolution
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measure of clarity of the image
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organelles
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subcellular structures
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electron microscope (EM)
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-focuses a beam of electrons through the specimen or onto its surface
-resolution inversely related to wavelength of radiation, and electron beams have wavelengths that are shorter than wavelengths of visible light -resolution of usually 2nm, but can go to.002 nm |
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cell ultrastructure
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cell's anatomy as revealed by an electron microscope
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size of cells
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diameter between 1 and 100 um
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name two types of electron microscopes
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scanning electron microscope (SEM) and the transmission electron microscope (TEM)
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scanning electron microscope (SEM)
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-useful for studying the surface of a specimen
-electron beam scans surface of sample (which is usually coated w/ a thin film of gold) -beam excites electrons on sample's surface -these secondary electrons are detected by a device that translates the pattern of electrons into an electronic signal to a video screen - creates image -image appears 3-dimensional |
