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29 Cards in this Set
- Front
- Back
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Who combined 2 lenses to fashion a crude microscope in 1590?
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Zacharias Janssen
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Which German astronomer improved the microscope?
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Johann Kepler
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Who was a linen draper who took a single lens, ground and polished resulting in magnification of 50 to 300 diameters?
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Anton van Leewenhoek
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What are the two basic types of microscope?
What are the 3 objectives of microscopy? |
1. Light and electron
2. a. magnify image b. maximize resolving power c. distinguish the components of the sample being viewed |
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What are the 4 types of LIGHT microscope?
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1. Bright field (used in the lab)
2. Dark field (limited use, for spirochetes) 3. Fluorescence (antigen and antibodies) 4. Phase contrast (view invertebrates) |
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A bright field microscope contains BLANK or more lenses
A BF microscope consists of (4)... |
TWO
1. Ocular lens 2. Nosepiece: objective lens 3. Iris diaphragm 4. Light intensity |
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Objective lenses, should be free of spherical, chromatic and other aberrations.
What are spherical and chromatic aberrations? |
spherical abs are distorted images
chromatic abs gives colored fringes |
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1. Most objective lenses are BLANK
2. What is resolving power, or resolution? |
1. Achromatic
2. The ability of a microscope to distinguish closely spaced objects as separate entities. |
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What is the resolving power of the light microscope?
What three factors affect resolving power? |
0.2 micrometers
1. Wavelength of the light 2. Numerical aperature of the condenser lens (NA) 3. Numerical aperature of the objective lens. |
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What is the medium through which the object is viewed which can increase the numerical aperature?
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Refractive index (RI)
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In light microscopy, what is empty magnification?
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magnification over 1000
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When is dark field microscopy useful? Name an example
The specimen appears BLANK against a BLANK background |
Useful for high contrast and small thin structures (ex: flagella)
Light...Dark |
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How is dark field microscopy developed?
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By placing a dark field stop in the center of the condenser.
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Who developed the phase contrast microscope? What is it's purpose?
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Zericke in 1932
It is used to study living organisms by detects small differences in refractive indices of the specimen and the surrounding background |
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How is the image in the phase contrast microscope developed?'
How is the specimen illuminated? |
1. Developed through the use of an annular aperature, diaphragm below the condenser.
2. the specimen is illuminated with a ring of light |
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Fluorescence occurs when materials absorb BLANK wavelengths of BLANK BLANK and then emit light of BLANK wavelengths.
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short
ultraviolet light longer |
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What is dye used in fluorescence microscopy?
How does it work? How is it used? |
fluorescein isothiocyanate aka FITC
It absorbs blue light and emit green light It is used and conjugated to antibodies to identify specimens |
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Immunofluorescence is used in...
Acridine orange can cause... |
diagnostic clinical microbiology.
mutations in bacteria |
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What is epifluorescence?
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incident light excitation
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Electron microscopes have a resolving power of BLANK micrometers, magnification of BLANK or greater.
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0.001
100,000x |
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What are the two types of electron microscope?
Electrons substitute light. The electron beams are BLANK shorter than WL of visible light |
TEM, transmission electron microscopes, and SEM, scanning electron microscopes.
100,000 |
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What two items are best viewed with an electron microscope?
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Viruses and bacteriophages
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T or F: In TEM, specimens are viewed alive.
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FALSE FOOL. They are fixed and embedded in plastic resin.
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What is the magnification of TEM and SEM?
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100,000x
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What is the purpose of SEM?
How does it work (basic)? |
Permits surface structure observation of a specimen through a 3D image.
It works by drying specimen, dehydrating in ethanol, and place in Freon gas chamber. Finally coated in thin metal layer. |
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What are two types of electron microscopes besides TEM and SEM? What is their magnification?
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Scanning tunneling microscope and atomic force microscope.
Both have 1,000,000x |
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How does STM work? What is it used for?
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Uses a probe with a single atom tip that traces the contours of a surface, used to image DNA and proteins.
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How does AFM work? What is it used for? How are Van der Waals forces involved?
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Probe traces the outline of atoms on the surface. Used for topographical image or viruses and red blood cells.
AFM measures van der Waals forces between the electron shells between adjacent atoms on the cell surface |
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NOTE: STUDY TABLE ON 4 TYPES OF LIGHT MICROSCPE
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NOW
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