bis_104_mid_exam_i__key_082 - Page 5

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c. Now suppose that your microscope light source has a wavelength of 500 nm. Using your 40x objective lens (an oil immersion lens with Numerical Aperture = 1.4), and a drop of immersion oil between your lens and the specimen, calculate the limit of resolution for this microscopic set up (2 pts) d = (0.61) (500 nm) / 1.4 = 218 nm (200nm – 225nm) acceptable d. The set up described above provides a certain magnification and resolution, but what about contrast (visibility)? Describe two different technical procedures that can be used to improve specimen contrast. (2) Modify the specimen by treating it with selective stains or vital dyes that will bind to and highlight specific organelles and cell components. Increase in contrast increases visibility. . Modify the optics of the microscope. Use phase-contrast or differential interference contrast (DIC) microscope
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Unformatted text preview: to convert diffracted light passing through the specimen to light vs dark contrast. e. Describe in general terms how the techniques of scanning confocal and deconvolution fluorescence microscopy can improve image resolution over that of conventional fluorescence microscopy. ( No need to compare the details of the two techniques, they both accomplish the same thing) (2 pts) Both of these technical modifications of std fluor. microscopy either physically (confocal) or mathematically (deconvolution) subtract out the fluorescence emissions that come from the fluorescence that is out of the focal plane. Therefore, the observer-detector sees only the fluor. that is in focus = sharper image. Page 1 Name ________________________ 1. For each of the items listed below, describe: (8 pts) Demo...
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This note was uploaded on 05/24/2010 for the course BIS 104 taught by Professor Scholey during the Spring '08 term at UC Davis.

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