bis_104_midterm_exam_i_key2_fall_07 - Page 3

bis_104_midterm_exam_i_key2_fall_07 - Page 3 - In addition,...

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Page 2 Name ____________________________________ 5. What is meant by the term, “empty magnification”? (2) Empty magnification occurs when a specimen is magnified without the benefit of increased resolution. 6. Without going into the detailed mechanisms, briefly describe how both scanning confocal fluorescence microscopy and deconvolution fluorescence microscopy improve on the images provided by conventional fluorescence microscopy. (2) Both techniques provide a sharper image of a specimen by blocking out or subtracting out all of the unfocused fluorescence from each optical plane of focus. 7. What advantages does indirect immunofluorescence have over direct immunofluorescence for visualizing cells and their components by fluorescence microscopy? (2) By providing more fluorochromes per target, the fluorescent emission signal is amplified and the signal is intensified in indirect immunofluor., therefore, it can be more sensitive.
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Unformatted text preview: In addition, fluor labeled secondary antibodies provide for more versatility and flexibility in detecting primary antibodies. 8. With the exception of egg cells, which can attain diameters in the millimeter range in some species, most somatic cells in eukaryotes are no larger than 30 40 micrometers (um) in diameter. Cite two possible reasons for this apparent restriction on the size of animal cells. (4) a) With one nucleus (diploid genome) per cell, there is a limit to the volume of cytoplasm that can be efficiently regulated by the genome. b) As cell volume increases the surface area to volume ration decreases to a point where exchange across the PM becomes inefficient for the volume of cytoplasm. c) Since the rate of diffusion drops off as the square of the distance of between sources, this important mechanism becomes less efficient with increase in cytoplasmic volume. Demo...
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