Chapter 6 - , focuses a beam of electrons through the...

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Chapter 6 Light microscope , visible light is passed through the specimen and then through glass lenses. Lenses refract light so that image is magnified as it is projected into the eye. Magnification, ratio of an object’s image size to its real size. Resolution, measure of the clarity of the image; minimum distance 2 points can be separated & still be distinguished as 2 points. Light microscopes cannot resolve detail finer than 0.2 micrometers (size of a small bacterium). Brightfield illumination- dark objects against bright background. Darkfield- opposite Confucal- uses flourochromes/laser light, 3-D images. Phase-constrant- accentuates diff. of the light that passes through a specimen Differential interference- acc. Diff. of light passes, 2 beams Flourescence- absorbs UV light, emits visible light Electron microscope
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Unformatted text preview: , focuses a beam of electrons through the specimen or onto its surface. Electrons have much shorter wavelengths than visible length. Scanning electron microscope, useful for detailed study of the surface of a specimen. 3-D image. Transmission electron microscope, used to study internal ultrastructure of cells. Not 3-D Cell fractioniation: takes cells apart/ separates the major organelles & other subcellular structures from one another. Instrument used is the centrifuge, which spins test tubes holding mixtures of disrupted cells at various speeds. Causes some cell components to settle to the bottom, forming a pellet. Enzymes found in the nucleus: DNA polymerase, RNA polymerase, DNA binding proteins, RNA binding/processing proteins. Fluid of the nucleus: nucleoplasm....
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