MICR 2420 Lecture Notes - Microorganism, Retina, Scanning Electron Microscope
20 May 2014
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Document Summary
0. 3-02 micrometers: fishelsoni up to 0. 6 mm lives in the gut of sturgeon fish surface area to volume ratio: Unicellular microoranisms need to get their nutrients from the environment via the cell membrane. Need to fix and stain (as most microorganisms are transparent) What are other differential stains? (other than gram stain) Microscopy that uses scattered/refracted light from the specimen viewed on a dark background. Light that passes through the medium does not reach the objective lens, while light scattered by the specimen does. Live or dead transforms changes refractive indexes in specimen into differences in light intensity, best for observing intracellular structures cells and their internal structures appear darker than the surrounding medium. How does phase-contrast microscopy work? superimposes refracted light and transmitted light shifted half a wavelength out of phase, creating destructive interference. Destructive interference between the two sorts of light when the image is projected results in the specimen appearing as a dark object.
