MIC 201 Ch4 Definitions
Terms
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- Light microscope
- look at intact cells
- Electron microscope
- look at internal structure or details of cell surfaces
- Resolution
- the ability to distinguish two adjacent points as separate
- Bright-field microscope
- consists of objective lens and ocular lens which function together to resolve (clear up) the image
- Product
- total magnification of objective and ocular lenses; limited by resolution
- Numerical aperture
- a measure of light-gathering ability
- oil-immersion lenses
- lenses that uses oil
- dye
- organic compounds; cationic (positively charged) and combine strongly with negatively charged cellular constituents
- phase contrast microscope
- improve contrast between cells and the surrounding medium, making it possible to see cells without staining them
- dark-field microscope
- lighting system modified to reach specimen from the sides only so it appears light on a dark background; see motility of microbe
- differential stains
- used in procedures that do not stain all kinds of cells equally
- gram stain
- divide gram-positive from gram-negative
- gram-negative
- a prokaryotic cell whose cell wall contains relatively little peptidoglycan but contains an outer membrane composed of lipopolysaccharide, lipoprotein, and other complex macromolecules
- gram-positive
- a prokaryotic cell whose cell wall consists chiefly of peptioglycan and lacks the outer membrane of gram-negative
- peptidoglycan
- a polysaccharide composed of alternating repeats of acetylglucosamine and acetyllmuramic acid with the latter in adjecent layers cross-linked by short peptides
- fluorescence microscope
- used to visualize specimens that fluoresce (emit light of one color when light of another color shines upon them)
- differential interference contrast (DIC)
- form of light microscopy that employs (uses) a polarizer to produce polarized light
- atomic force microscope
- a tiny stylus is positioned extremely close to the specimen such that weak repulsive atomic forces are established btween the probe and the specimen
- confocal scanning laser microscopy
- computerized microscope that couples a laser light source to a light microscope
- transmission electron microscope
- electrons are used and electromagnets function as lenses
- scanning electron microscope
- electron beam scans back and forth
- morphology
- shape of organism
- coccus/cocci
- spherical or ovoid
- rod
- cylindrical shape
- spirilla
- curved rods that spiral
- spirochetes
- tightly coiled bacteria
- appendaged and budding bacteria
- extension to cells; hypha and stalk
- filamentous bacteria
- long, thin cells or chains of cells