BactCells121_OLS

BactCells121_OLS - A Bit of Info About Microscopy Light...

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A Bit of Info About Microscopy Light Microscopy 1. 2. Light source is visible light 3. Light microscopes have one ocular (10X) and a minimum of 3 objectives (10X, 40X, 100X) 4. Total magnification = mag of ocular X mag of objective 5. Maximum magnification is 1000X 6. Small specimens (like bacteria) are usually stained in some way to make them more clearly visible Dark-field Microscopy 1. Modification of light microscopy using indirect lighting rather than direct 2. Specimens appear light against a dark background 3. Used for viewing live, unstained specimens 1. Specimen is coated with fluorescent dye(s) 2. Light source is ultraviolet light (fluorescence microscopy) or a laser (confocal microscopy) 3. Specimens “glow” against a dark background Electron Microscopy 1. Magnets serve as “lenses” and an electron beam serves as the “light source” 2. Critical invention that allows viewing of specimens too small to be viewed with light microscopes (viruses and internal cell structures) 3. Scanning electron microscopy (SEM) allows viewing of the surface of the specimen (up to 100,000X magnification) in 3-dimensions 4. Transmission electron microscopy (TEM) allows viewing of internal structures of the specimen (up to 20,000,000X magnification) in “flat” 2-dimension 1
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Bacterial Cells Organization of a Typical Bacterial Cell: I. External Structures
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BactCells121_OLS - A Bit of Info About Microscopy Light...

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