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Microbiology
Observing Microorganisms Through a Microscope
| Question | Answer |
|---|---|
| The electrons pass through a thin section of the specimen | TRANSMISSION ELECTRON MICROSCOPE |
| Visible light passes through the specimen; uses separate objective and ocular lenses. | COMPOUND LIGHT MICROSCOPE |
| Details become visible because of differences in the refractive index of different parts of the cell. | PHASE-CONTRAST MICROSCOPE |
| Visible light is scattered after striking the specimen, and the specimen is visible against a darkened background. | DARKFIELD MICROSCOPE |
| A special microscope using ultraviolet illumination. | FLUORESCENCE MICROSCOPE |
| The electrons strike the surface of the specimen, and secondary electrons leaving the surface are viewed on a television-like screen | SCANNING ELECTRON MICROSCOPE |
| Pertaining to the relative velocities of light through a substance. | REFRACTIVE INDEX |
| Involves the use of antibodies and ultraviolet light. | IMMUNOFLUORESCENCE |
| One millionth of a meter | NANOMETER |
| One ten-billionth of a meter. | ANGSTROM |
| The ability to separate two points in a microscope field. | RESOLVING POWER |
| Adhere(s) best to bacteria, which have a negative charge, because the color molecule has a positive charge. | BASIC DYES |
| Used in diagnosis of tuberculosis | ACID-FAST STAIN |
| Involve(s) the use of a negative stain made from India ink particles. | CAPSULE STAIN |
| Schaeffer-Fulton stain | ENDOSPORE STAIN |
| Use(s) carbolfuchsin dye. | ACID-FAST STAIN |
| Use(s) malachite green. | ENDOSPORE STAIN |
| Reflect(s) a basic difference between microbial cell walls; ethanol will not remove stain from bacteria. | GRAM STAIN |
| A microscope that uses laser illumination | CONFOCAL |
| Extremely thin microbes, for example, the spirochete Treponema pallidum, are best seen with this type of light microscope. | TRANSMISSION |
| This type of electron microscope yields images with seemingly three-dimensional views of the specimen. | SCANNING |
| Light rays that pass through different portions of the specimen reach the eye with their wave-peaks reinforced or cancelled, making structures of the specimen relatively light or dark. | PHASE CONTRAST |
| Formerly known as a micron | MICROMETER |
| Formerly known as a millimicron | NANOMETER |
| This is 10 the the -10th of a meter | ANGSTROM |
| A billionth of a meter | NANOMETER |
| About the highest magnification possible in a compound light microscope is ______________________ | 2000 |
| Immersion oil has about the same refractive index as ________________ | GLASS |
| Fluorochrome dyes glow with visible light when illuminated by _________________________ light. | ULTRAVIOLET |
| Electron wavelengths are only about 1/100,000 as long as visible light and therefore have much _______________ resolving power. (better, poorer) | BETTER |
| Bacteria tend to have slightly __________ electrical charge. (positive, negative) | NEGATIVE |
| The thin film of a microbial suspension spread on the surface of a slide is called a ________________. | SMEAR |
| Flaming the slide before applying the stain is called ____________. | FIXING |
| Transmission electron microscopy permits magnifications as high as about 10,000 times to _____________. | 100,000 times |
| In the flagella stain, a _____________ is used to increase the diameter of the flagella. | MORDANT |
| Two bacterial genera that are acid-fast are ____________ and _________________. | MYCOBACTERIUM, NOCARDIA |
| A disease for which the acid-fast stain is useful in diagnosis is ____________. | TUBERCULOSIS OR LEPROSY |
| In order to see shapes and arrangements of cells, a _____________ stain is usually sufficient. | SIMPLE |
| _______________ dyes have a negative color ion. (acidic, basic) | ACIDIC |
| The equation that describes the resolving power (RP) of a microscope is RP=wavelength of illumination/2 X Numerical Aperture. If the wavelength of light is 0.52 um, what is the resolving power? Numerical aperture of an oil immersion object is usually 1.30 | About 0.2 um |
| What type of microscopy would be most appropriate to identify pathogenic bacteria in clinical specimens? | FLUORESCENCE MICROSCOPY |
| What type of microscopy would be most appropriate to view objects smaller than 0.2 um, such as viruses? | ELECTRON MICROSCOPY |
| What type of microscopy would be most appropriate to view heat-fixed, stained bacterial cells? | BRIGHTFIELD MICROSCOPY |
| What type of microscopy would be most appropriate to view microorganisms that can't be stained by standard methods, such as Treponema pallidum? | DARKFIELD MICROSCOPY |
| What type of microscopy would be most appropriate to view the internal structure of living microorganisms? | PHASE-CONTRAST MICROSCOPY |
| What stain or technique would be most appropriate to detect bacterial capsules and evaluate an organism's virulence? | A NEGATIVE STAIN USING INDIA INK OR NIGROSIN. IT STAINS THE BACKGROUND BUT DOESN'T PENETRATE THE CAPSULE. THE CAPSULE SHOWS UP AS A HALO SURROUNDING THE CELL AGAINST A DARK BACKGROUND |
| What stain or technique would be most appropriate to provide the necessary contrast for viewing specimens with a compound light microscope | A SIMPLE STAIN SUCH AS SAFRANIN OR METHYLENE BLUE WILL WORK FINE |
| What stain or technique would be most appropriate to diagnose infections of Mycobacterium or Nocardia? | ACID-FAST STAINING WOULD BE APPROPRIATE. THE RED DYE, CARBOLFUCHSIN, BINDS STRONGLY TO A WAXY SUBSTANCE IN THE CELL WALL OF THESE ORGANISMS BUT NOT TO OTHER NONACID FAST BACTERIA |
| What stain or technique would be most appropriate to help determine what antibiotic will be most effective against a certain disease organism? | THE GRAM STAINING REACTION IS HELPFUL INFORMATION WHEN CHOOSING AN ANTIBIOTIC, WHICH OFTEN SHOWS SPECIFICITY FOR EITHER GRAM+ OR GRAM- BACTERIA. |
| Why do gram positive cells retain the crystal violet through the alcohol wash of Gram staining, whereas gram negative cells do not? | WHEN IODINE IS ADDED TO A SMEAR AFTER PREVIOUS STAINING WITH CRYSTAL VIOLET THEY COMBINE TO FORM A COMPLEX THAT IS LARGER THAN THE CRYSTAL VIOLET MOLECULE THAT INITIALLY ENTERED THE CELLS. IT IS TOO LARGE TO BE WASHED OUT. |
Created by:
Micheleledet17
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