observing microorganisms

micrometers and nanometers

microorganisms are measured in…

acid fast stain

identifies mycobacterium

order of gram stain

violet, mordant (iodine), alcohol, safranin

staining steps

fix using heat, iodine (mordant), alcohol (decolorizer), safranin (counterstain)

simple stain

single basic dye, mordant improves bonding

endospore and flagella stains

visualize structures in bacterial cells

negative staining

makes microbial capsules viable

differential stains

differentiate bacteria based on reaction to stain, ex. gram pos are purple

total magnification

objective lens x ocular

resolution

ability of lenses to distinguish 2 points, shorter wavelengths → greater ___

electron microscopy

beam of electrons

darkfield microscopy

detecting the presence of extremely small organisms

phase-contract microscopy

accentuates diffraction of light that passes through specimen, used on cells that cannot be fixed or stained

differential interference contrast microscopy

fluorescence microscopy

uses UV light, fluroescent substances absorb UV light and emit longer wavelength light

scanning acoustic microscopy

based on the interpretation of sound waves through a specimen, studies living cells attached to surfaces (ex. biofilms)

bright field illumination

dark objects visible against light background

transmission electron microscopy

produces thin sections of organisms

scanning electron microscope

electron gun produces a beam of electrons that scans the surface of an entire specimen

scanning acoustic microscope

measures sound waves reflected

objective lense x ocular lense

total magnification

immersion oil

keeps light from refracting

stains

used with brightfield illumination

unstained

observed using darkfield, phase-contrast, or DIC microscopy