microbiology 2
Terms
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- cationic dye
- (also called basic dye) an ionic compound, used for staining bacteria, in which the positive ion imparts the color
- resolving power
- a numerical measure of the resolution of an optical instrument
- wet mount
- microscopy technique in which a drop of fluid containing the organisms (often living) is placed on a slide
- microscopy
- the technology for making very small things visible to the unaided eye
- compound light microscope
- a light microscope with more than one lens
- body tube
- microscope part that conveys an image from the objective to the eyepiece
- diffraction
- Phenomenon in which light waves, as they pass through a small opening, are broken up into bands of different wavelengths
- immersion oil
- substance used to avoid refraction at a glass-air interface when examining objects through a microscope
- flourescent antibody staining
- procedure in flourescence microscopy that uses a flourochrome attached to antibodies to detect the presence of an antigen
- iris diaphragm
- adjustable device in a microscope that controls the amount of light passing through the specimen
- binocular
- referring to a light microscope having two eyepieces (oculars)
- fine adjustment
- focusing mechanism of a microscope that very slowly changes the distance between the objective lens and the specimen
- electron micrograph
- a "photograph" of an image taken with an electron microscope
- stain
- (also called dye) a molecule that can bind to a structure and give it color
- dark-field illumination
- in light microscopy, the light that is reflected from an object rather than passing through it, resulting in a bright image on a dark background
- flagellar staining
- a technique for observing flagella by coating the surfaces of flagella with a dye or a metal such as silver
- mechanical stage
- attachment to a microsope stage that holds the slide and allows precise control in moving the slide
- light microscopy
- the use of any type of microscope that uses visible light to make specimens observable
- scanning tunneling microscope (STM)
- also called scanning probe microscope; type of microscope in which electrons tunnel into each other's clouds, can show individual molecules, live specimens, and work underwater
- luminescence
- process in which absorbed light rays are reemitted at longer wavelengths
- flourescence microscopy
- use of ultraviolet light in a microscope to excite molecules so that they release light of different colors
- condenser
- device in a microscope that converges light beams so that they will pass through the specimen
- freeze-etching
- technique in which water is evaporated under vacuum from the freeze-fractured surface of a specimen before the observation with electron microscopy
- phosphorescence
- continued emission of light by an object when light rays no longer strike it
- resolution
- the ability of an optical device to show two items as separate and discrete entities rather than a fuzzily overlapped image
- transmission
- the passage of light through an object
- Schaeffer-Fulton spore stain
- a differential stain used to make endospores more visible
- active site
- area on the surfaceof an enzyme to which its substrate binds
- atomic force microscope (AFM)
- advanced member of the family of scanning tunneling microscopes, allowing 3-dimensional views of structures from atomic size to about 1mm
- ocular micrometer
- a glass disk with an inscribed scale that is placed inside the eyepiece of a microscope; used to measure the actual size of an object being viewed
- shadow casting
- the coating of electron microscopy specimens with a heavy metal, such as gold or palladium, to create a three-dimensional effect
- differential stain
- use of two or more dyes to differentiate among bacterial species or to distinguish various structures of an organism; for example, the Gram stain
- objective lens
- lens in a microscope closest to the specimen that creates an enlarged image of the object viewed
- micrometer
- (mm) unit of measure to 10^-6m; formerly called a micron (m)
- refraction
- the bending of light as it passes from one medium to another medium of different density
- scanning electron microscope (SEM)
- type of electron microscope used to study the surface of specimens
- absorption
- process in which light rays are neither passed through nor reflected off an object but are retained and either transformed to another form of energy or used in biological processes
- total magnification
- obtained by multiplying the magnifying power of the objective lens by the magnifying power of the ocular lens
- simple stain
- a single dye used to reveal basic cell shapes and arrangement
- bright-field illumination
- illumination produced by the passage of visible light through the condenser of a light microscope
- anionic dye
- (also called acidic dye) an ionic compound, used for staining bacteria, in which the negative ion imparts the color
- transmission electron microscope (TEM)
- type of electron microscope used to study internal structures of cells; very thin slices of specimens are used
- numerical aperture
- the widest cone of light that can enter a lens
- electron microscope
- microscope that uses a beam of electrons rather than a beam of light and electromagnets instead of glass lenses to produce an image
- Angstrom (A)
- unit of measurement equal to 10210m - no longer officially recognized
- index of refraction
- a measure of the amount that light rays bend when passing from one medium to another
- parfocal
- for a microscope, remaining in approximate focus when minor focus adjustments are made
- monocular
- refers to a light microscope having one eyepiece (ocular)
- flouresce
- emission of light of one color when irradiated with another, shorter wavelength of light
- freeze-fracturing
- technique in which a cell is first frozen and then broken with a knife so that the fracture reveals structures inside the cell when observed by electron microscopy
- phase-contrast microscopy
- use of microscope having a condenser that accentuates small differences in the refractive index of various structures within the cell
- reflection
- the bouncing of light off an object
- negative staining
- technique of staining the background around a specimen, leaving the specimen clear and unstained
- Ziehl-Neelsen acid-fast stain
- a differential stain for organisms that are not decolorized by acid in alcohol, such as the bacteria that causes Hansen's disease (leprosy) and tuberculosis
- heat fixation
- technique in which air-dried smears are passed through an open flame so that organisms are killed, adhere better to the slide, and take up dye more easily
- smear
- a thin layer of liquid specimen spread out on a microscope slide
- hanging drop
- a special type of wet mount often used with dark-field illumination to study motility of organisms
- ocular lens
- lens in the microscope that further magnifies the image created by the objective lens
- Nomarski microscopy
- differential interference contrast microscopy; utilizes differences in refractive index to visualize structures, producing a nearly three dimensional image
- nanometer
- (nm) unit of measure equal to 10^-9m; formerly called a millimicron (mm)
- Gram stain
- a differential stain that uses crystal violet, iodine, alcohol, and safranin to differentiate bacteria. Gram-positive bacteria stain dark purple; Gram-negative ones stain pink/red
- coarse adjustment
- focusing mechanism of a microscope that rapidly changes the distance between the objective lens and the specimen
- mordant
- a chemical that helps a stain adhere to the cell or cell structure