microscopy and differential staining Essay

787 WordsJan 6, 20144 Pages
1.What are the advantages and disadvantages of the different types of light and electron microscopes discussed in Chapter 3 that are used to study microorganisms? Focus your response in terms of the following parameters: ◦Range of magnification ◦Resolving ability ◦Sample preparation ◦Possible states of sample (e.g. whole organism, part of, living, non-living, etc.) 2.What type of microscope would you use to investigate each of the following scenarios and why (your answer to question 1 will help): ◦Determine the relative sizes of two eukaryotic cells. ◦Determine how many bacteria are dying after a chemical treatment. ◦Determine where in a eukaryotic cell a particular protein is localized. ◦Identify a virus from a contaminated…show more content…
-not necesary to fix or stain specimen. -internal structures of a cell more sharply defined -Electron Microscopes: Beam of electrons used instead of light. -Objects smaller than 2.0μm such as viruses must be examined with this type of microscope-resolving power much greater because wavelength of electrons is 100,000 times smaller than the wavelengths of visible light. -images are always black and white, but they can be colored to accentuate certain details -use electromagnetic lens instead of glas lens used by light microscopes - two types of electron microscopes: Transmission electron microscope : -Can resolve objects as close as 1PM and objects are generally magnified 10,000 to 100,000X. -only very thin section of specimen can be studied effectiviely. Thus specimen has no three-demensional aspect. -specimens must be fixed , dehydrated andviewed under high vacuum to prevent electron shattering and these treatments not only kill the specimen,but also cause shrinkage and distortion. Scanning Electron Microscopy :-overcomes the problem of sectioning associated with transmission electronmicroscope -striking three dimensional views. -especially useful in studying the surface structures of intact cells and viruses -resolves
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