microbio microscopy

light microscopes

brightfield

darkfield

phase contrasts

differential interference contrast (DIC)

fluorescent contrasts

describe brightfield microscopes

fixed, stained specimen =, 1000x-2000x oil immersion

white light , dark against light illuminated background

describe darkfield microscopes

opaque disk over light source, unstained + live, makes background dark

describe phase contrasts

two sets of light brought together (light source + light detracted from structures in the specimen; creates sharp images of internal structures in specimen)

describe DIC

2 beams of light from light source; almost 3D image of a specimen

describe fluorescent contrast

fluorescent light absorbs short wavelength of light; emits light as longer wavelengths; immunofluorescence (antibodies)

types of fluorescent contrasts

confocal

two photon microscope

super resolution

describe confocal

fluorescent, using short wavelengths of light (blue), pinhole aperture (significantly reduces the blurring of the light —> sharp image) increases resolution; 3-D images

describe two photon microscope

longer wavelength (red); deeper/thicker image of specimen; can image cells up to 1 millimeter (mm) deep

describe super resolution

nanometer scale (10^-9)

describe scanning acoustic

sound waves to create a computerized image; biofilms

describe transmission electron (TEM)

electrons, 10,000-10,000,000 picometer scale 10^-12pm, focus on internal structure of cell (drawback: specimen is very thin, no more than 100nm thick) BLACK and WHITE

Scanning electron microscope (SEM)

1000x-500,000x ; 10nm scale surface structure and creates 3D images of specimen IN COLOR

describe scanning probe microscope

uses probe to examine specimens with electrical current, scanning tunneling, tungsten probe, observes atoms, resolution: 1/100 size of atom, detailed view of molecules

describe atomic force

metal and diamond probe to scan surface, creates 3D image

describe simple stains

single basic dye

mordant if necessary to (improve bond between specimen + stain)

types differential stains

gram-stain and acid- fast

describe gram-stains

distinguish types of bacteria cell wall, used to categorize bacteria: gram + (positive) or gram - (negative)

stains used for gram-stains

crystal violet (purple) (+) and safranin (pink/red) (-)

describe acid-fast stain

specimen stained by carbofusion (red) or methylene (blue)

types of special stains

negative stains: capsules (layer of sugar outside cell)

endospores

flagella

what is resolution

how well the microscope distinguishes 2 points as separate

what is refraction

bending (way your eye perceives) o flight as it passes from one medium to another

what is magnification

how much larger a specimen appears compared to the actual size, using 2 measurements (objective x ocular)