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46 Cards in this Set
- Front
- Back
1 um
is equal to how many meters? |
10^-6 m
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light microscopy
define |
the use of any kind of microscope that uses visible light to observe specimens
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compound light microscope
components |
has a series of lenses
uses visible light as its source of illumination |
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illuminator
definition |
light source
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condenser
definition |
lenses that direct the light rays through the specimen
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objective lenses
definition |
the lenses closest to the specimen
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ocular lens
definition |
eyepiece
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total magnification
how to calculate |
multiply
objective lens by ocular lens |
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resolution
definition |
the ability of the lenses to distinguish fine detail and structure
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refractive index
definition |
a measure of the light-bending ability of a medium
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darkfield microscopy
what is it used for? |
examining live microorganisms that either are...
invisible in the ordinary light microscope cannot be stained by other methods, are so distorted by staining that their characteristics then cannot be identified |
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phase-contrast microscopy
what is it used for? |
detailed examination of internal structures in living microorganisms
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differential interference contrast microscopy
(DIC) how does it work? |
uses differences in refractive indexes
uses two beam of light instead of one |
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fluorescence microscopy
what is it used for? |
for fluorescent-antibody techniques to rapidly detect and identify microbes in tissues or clinical specimens
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brightfield microscopy
what is it used for? |
to observe various stained specimens and to count microbes
does not resolve very small specimens, such as viruses |
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differential interference contrast microscopy
what is it used for? |
to provide 3D images
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confocal microscopy
what is it used for? |
to obtain 2D and 3D images of cells for biomedical applications
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confocal microscopy
how does it work? |
uses laser light to illuminate one plane of a specimen at a time
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scanning acoustic microscopy
what is it used for? |
to examine living cells attached to another surface
such as cancer cells, artery plaque, and biofilms |
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scanning acoustic microscopy
how does it work? |
uses a soundwave of specific frequency that travels through the specimen with a portion being reflected when it hits an interface within the material
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electron transmission microscopy
what is it used for? |
to examine viruses or the internal ultrastructure in thin sections of cells
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electron transmission microscopy
magnification |
10,000 - 100,000x
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electron transmission microscopy
how does it work? |
uses a beam of electrons instead of light
electrons pass through the specimen |
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electron scanning microscopy
what is it used for? |
to study the surface features of cells and viruses
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electron scanning microscopy
magnification |
1,000-10,000x
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electron scanning microscopy
how is it used? |
uses a beam of electrons instead of light
electrons are reflected from the specimen |
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scanned-probe scanning tunneling microscopy
what is it used for? |
provides very detailed views of molecules inside cells
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scanned-probe scanning tunneling microscopy
how does it work? |
uses a thin metal probe that scans a specimen and produces an image revealing the bumps and depressions of the atoms on the surface of the specimen
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gram stain process
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1. heat-fixed smear is covered with a basic purple dye (primary stain)
2. purple dye is washed off and the smear is covered with iodine, a mordant. iodine is washed off. 3. the slide is washed with alcohol or an alcohol-acetone solution (decolorizing agent) 4. the alcohol is rinsed off, and the slide is then stained with safranin, a basic red dye. the smear is washed again, blotted dry, and examined microscopically |
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primary stain
what does it do? |
imparts its color to all cells
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decolorizing agent
what does it do? |
removes the primary stain from the cells of some species but not from others
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gram positive
what color are they? |
violet
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gram negative
what color are they? |
pink/red
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gram positive bacteria
characteristic |
thicker peptidoglycan cell wall
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acid-fast stain
is used to identify what bacteria? |
genus Mycobacterium
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Mycobacterium
two examples |
Mycobacterium leprae
Mycobacterium tuberculosis |
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acid-fast stain
procedure |
1. the red dye carbolfuchsin is applied to a fixed smear, and the slide is gently heated. then cooled and washed with water.
2. smear is treated with acid-alcohol (a decolorizer) which removes the red stain from bacteria that are not acid-fast. the acid-fast microorganisms RETAIN the red color. 3. smear is stained with a methylene blue counterstain. non-acid-fast cells appear blue. |
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negative staining
is used for what? |
to demonstrate the presence of a capsule
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simple stain
is used for what? |
to highlight microorganisms to determine cellular shapes and arrangements
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what are the two differential stains?
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gram and acid-fast
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what are the three special stains?
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negative
endospore flagella |
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gram stain
is used for what? |
to distinguish among different kinds of bacteria
classifies bacteria into gram positive and gram negative |
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acid-fast stain
is used for what? |
to distinguish Mycobacterium species and some species of Nocardia
Acid-fast bacterium remain red |
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special stains
are used for what? |
to color and isolate various structures, such as capsules, endospors, and flagella
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negative stains
are used for what? |
to demonstrate the presence of capsules
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endospore stains
are used for what? |
to detect the presence of endospores in bacteria
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