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44 Cards in this Set
- Front
- Back
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How many lenses does a simple microscope have? |
1 |
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Light microscopy |
Microscopes that use visible light to observe specimens |
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6 Types of Microscopy |
Compound light microscopy Darkfield microscopy Phase-contrast microscopy Differential interference contrast microscopy Fluorescence microscopy Confocal microscopy |
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Compound Light Microscopy |
the image from the objective lens is magnified again by the ocular lens |
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Total Magnification |
objective lens × ocular lens |
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REsolution |
the ability of the lenses to distinguish two points |
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Do longer or shorter wavelengths of light provide a better resolution? |
Shorter; but they also damage the cells. |
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Refractive Index |
measure of the light-bending ability of a medium |
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Brightfield Illumination |
Dark objects are visible against a bright background Light reflected off the specimen does not enter the objective lens |
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Darkfield Illumination |
Light objects are visible against a dark background Light reflected off the specimen enters the objective lens |
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Phase Contrast Microscopy |
Accentuates diffraction of the light that passes through a specimen |
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Differential Interference Contrast Microscopy |
Accentuates diffraction of the light that passes through a specimen; uses two beams of light |
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Fluorescence Microscopy |
Uses UV light Fluorescent substances absorb UV light and emit visible light |
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Flurochromes |
Fluorescent dyes |
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Confocal Microscopy |
Cells stained with fluorochrome dyes Short wavelength (blue) light used to excite the dyes The light illuminates each plane in a specimen to produce a three-dimensional image Up to 100 µm deep |
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Two-Photon Microscopy |
Cells stained with fluorochrome dyes Two photons of long- wavelength (red) light used to excite the dyes Used to study cells attached to a surface Up to 1 mm deep |
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Electron Microscopy |
* The shorter wavelength of electrons gives greater resolution
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In electron microscopy, what might specimens be stained with? |
heavy metal salts |
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Transmission Electron Microscopy (TEM) |
10,000–100,000×; resolution 2.5 nm |
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Scanning Electron Microscopy (SEM) |
An electron gun produces a beam of electrons that scans the surface of a whole specimen 1,000–10,000×; resolution 20 nm |
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Staining |
Coloring the microbe with a dye that emphasizes certain structures |
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SMearing |
A thin film of a solution of microbes on a slide |
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Fixing |
to attach the microbes to the slide and to kill the microbes |
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Examples of chemicals used to fix microbes to slides: |
methanol or heat can be used as fixatives |
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What do stains consist of that allow the stain to attach to the molecule? |
a positive and negative ion |
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In a basic dye, the chromophore is a |
chromophore is a cation |
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In an acidic dye, the chromphore is an |
anion |
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Negative Staining |
Staining the background instead of the cell |
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Simple Stain |
Use of a single basic dye |
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Mordant |
used to hold the stain or coat the specimen to enlarge it |
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Differential Stains |
Used to distinguish between bacteria |
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Examples of Differential Stains: |
Gram stain & Acid-fast stain |
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Gram-stain |
Classifies bacteria into gram-positive |
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Gram+ Bacteria |
tend to be killed by penicillin and detergents |
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Gram- Bacteria |
are more resistant to antibiotics |
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Acid-fast stain |
Stained waxy cell wall is not decolorized by acid-alcohol |
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Which type of bacteria must be stained using the Acid-Fast stain method? |
Mycobacterium Nocardia |
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Negative staining is useful for? |
Capsule |
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What is required to drive a stain into endospores? |
Heat |
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What does flagella staining require to make the flagella wide enough to see? |
a mordant |
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Gram+ bacteria stain |
purple |
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Gram-bacteria stain |
pink |
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Acid-fast bacteria stain |
pink
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non acid-fast bacteria stain |
blue |
