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23 Cards in this Set
- Front
- Back
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Light microscope allows us to observe.....
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.3 micrometers to 10 micrometers.
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How does magnification occur in a microscope?
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light is bent as it travels through the lens. The lens is curved.
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Name from bottom to top the way a microscope works.
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Lamp (or electron gun)>condensor lens>specimen>objective lens>image>ocular lens>eye (viewing screen)
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What acts on the light source?
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Condenser lens.
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Resolution (resolving power)
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ability to distinguish between 2 small objects close together
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Formula for resolution
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d = .5 λ/NA
λ = wavelength NA = numerical aperture |
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As wavelengths get _____ the resolution gets better.
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shorter
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Wavelength of electrons is dependent on ______
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applied voltage.
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Positive simple stains
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dyes bind to the microbe's CM
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Negative simple stains
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Don't stain the microbe, only the area around it.
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Simple (+ and -) stains reveal....
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general shape, size, and type of growth.
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_____ dyes do not require heat fixing.
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Negative. The specimens can still be alive.
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To view most microbes, what objective?
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100X and oil.
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India ink is used in...
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negative simple stain.
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Techniques to observe live unstained cells.
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Dark field, phase-contrast, differential intereface microscopy.
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Both _____ and ______ use visible light sources.
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dark field and phase contrast
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How is dark field used?
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uses alternate optics such that only light that is reflected by the specimen forms and image.
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How is phase contrast used?
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optics are sued to emphasize slight differences in refractive index of cells or subcellular structures.
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Differential Interface contrast microscopy is used....
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to see small differences in refractive indeces as different colors of light.
Structures are live and unstained, and the light is plane-polarized visible light. |
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Fluorescence microscopy is used...
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by being tagged with a fluorescent tag. Tags are fluorescent dyes covalently attached to antibodies that are specific for unique antigen determinant.
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Explain electron microscopy.
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The same as light microscopy except, light source is an electron beam and lenses are electromagnets. Is also done in a vacuum, so specimen is dead. Can have high resolution.
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Explain scanning electron microscopy.
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Visualizes 2^0 electrons ejected from the surface features that are then captured.no magnifying lenses. source of 2^0 electrons are from electron dense dye.size range from nm to cm but resolution is 10x less than TEM.
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Explain confocal scanning laser.
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uses computer integration of images from many different focal planes to generate 3D image. Uses fluorescent dyes attached to antibodies and laser light source.
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