Microscopy

cells are microscopic

light microscope,electron microscope

microscope->instrument to observe microorganism

produced a magnified image of the specimen

separate the details in the image

render the details visible to the human eye or camera

iodine,methylene blue,eosin Y,Toluidene blue,Wright's stain,crystal violet,aceto-orcein,Sudan III

eukaryotic cells,nucleus,most bacteria,mitochondrion

properties of light

absorption,transmission,reflection,refraction

magnification due to objective lens or ocular lens

mycoplasma,viruses,ribosomes,proteins,lipids,small molecules,atoms

smears

preparing smear

fixation

staining

simple staining

differential staining

special staining

wet mount

metric system

microbes and structural components->micrometers,nanometers,angstroms

bright-field microscope

produce dark image against a brighter background

dark-field microscope

produce a bright image of the object against a dark background

used to observe living,unstained preparations

used to observe internal structures in eukaryotic organism

used to identify bacteria such as Trepanoma pallidum,the causative agent of syphilis

image is formed by light reflected or refracted by specimen

phase contrast microscope

converts differences in refractive index/cell density into detected variations in light intensity

stain is not necessary,view internal structures of living organisms

excellent way to observe living cells

some light rays from hollow cone of light passing through unstained cell slowed/out of phase(dark against bright background)

electron microscope

employs a beam of electron in place of light wave to produce the magnified image

the wavelength of electron microscope is only 0.01 Ǻ

resolving power 100 times than light microscopes

fluorescence microscope

exposes specimen to UV ,violet or blue light

specimens usually staubed with fluorochromes

shows a bright image of the object resulting from the fluorescent light emitted by the specimen

has application in medical microbiology and microbial ecology studies

scanning electron microscope

transmission electron microscope

confocal microscopy

size of the image or point

the ability to distinguish two adjacent points

image formed by action of more than 2 lenses

uses visible light as a source of illumination

illuminator,condenser,objective lenses,ocular lenses

objective lenses magnification (10x,40x and 100x/oil-immension lens.)

ocular lenses magnification(10x)

total magnification=objective lens magnificationxocular lens magnification