tools of the laboratory Flashcards
what is identification of microorganism?
to attach a name or identity to the microbe using information gathered from inspection and investigation.
incubation of microorganism
inoculated media are placed in a controlled environment incubator to promote health
inspection of microorganism
cultures are observed for the macroscopic appearance of growth and development
isolation of microorganisms
some inoculation techniques can separate microbes to create isolated colonies that each contain a single type of microbe
ability to enlarge objects
magnification
ability to show detail
resolving power
magnification in most microscopes results from an interaction between
visible light waves and the curvature of a lens
of the final image is a product of the separate magnifying powers if the two lenses
total magnification
what is the total magnification consist of
objective power x ocular power = total magnification
the capacity to distinguish or separate two adjacent objects and depends on
resolution
most widely used specimen is darker than surrounding field used for live and preserved stained specimens.
bright-field
brightly illuminated specimens surrounded by darker=field used for live unstained specimens
dark-field
transforms subtle changes in light waves passing through the specimens into differences in light intensity best for observing intracellular structures
phase-contrast
modified microscope with an ultraviolet radiation source and filter uses dyes that emit visible light when bombard with shorter UV rays useful for diagnosing infections
fluorescence microscope
uses a laser beam of light to scan the specimen integrates images to allow focus on multiple depths or planes
scanning confocal microscope
forms an image with a beam of electrons that can be made to travel in wavelike patterns when accelerated to high speeds electron waves are 100,000 times shorter than waves of visible light magnification between 5,000x and 1,000,000x used to see viruses
electron microscope
transmit electrons through the specimen
transmission electron microscope (TEM)
provide detailed three-dimensional view
scanning electron microscope (SEM)
what are dyes used for
to create contrast by imparting color
cationic positively changed chromophore
basic dyes
surfaces of microbes are negatively charged and attracted basic dyes
positive staining
one dye is used revels shape size and arrangement
simple stains