ch 2 Flashcards
wavelength
distance between peaks
amplitude
height of each peak
frequency
rate of vibration of wave or the number of wavelengths
what is the refraction index ?
degree of change in transmission speed
refraction?
if light enters a substance with a HIGHER refractive index it SLOWS DOWN and bends TOWARDS the normal lint (AWAY from the boundary)
what occurs with a convex lens ?
meets a focal point
ex: glasses, contact lenses
what occurs with a concave lens?
refracts light away from a focal point
ex: flashing light
CAVE=FLASHLIGHT
what is contrast?
create of stark difference in COLOR
what is resolution?
ability to tell that two separate points or objects are separate
number of pixels
who used a compound microscope ?
galileo galilei
who used the 1st simple microscope?
leeuwenhoek
who coined the term cells?
robert hooke
what adjusts the light intensity on a bright field microscope ?
rheostat
bright field microscope
produces an image on a bright background
dark field
-producing a brighter image on a dark background
- useful for viewing live specimens
phase contrast
-high contrast
-high resolution
-w/o staining
-used for viewing live specimens and structures such as endospores and organelles
differential interference contrast (DIC)
-3d appearance
-makes it useful in distinguishing structures within live, unstained specimens
-images reveal detailed structures within cells
fluorescence
-uses fluorescent stains
-distinguish between living from dead cells
-or to find locations of particular molecules within a cell
confocal
-uses a laser to scan multiple a planes
-useful for examining thick specimens such as biofilms
two photon
Uses a scanning technique fluorochromes and long wavelength light (infrared) to penetrate deep into taking specimens such as biofilms 
transmission (TEM)
Uses electron beams that passed through a specimen to visualize small images; useful to observe small thin specimens such as tissue sections and subcellular structure
Scanning (SEM)
uses electron beams to visualize surfaces; useful to observe the 3d surface details of specimens
scanning tunneling (STM)
Works best on conducting material but can also be used to tell me organic materials such as DNA
atomic force (AFM)
Useful to observe specimens at the atomic level and can be more easily used with non-conducting samples
wet mount
good for viewing a life specimen
fixed mount
smear; good for staining
basic stain
-Positively charged ions
-basic fuchsin crystal violet, malachite green, safranin methylene blue
acid stain
-Negatively charged ions
-eosin, Rose Bengal, acid fuchsin
Positive stain
Dye/scene is absorbed into the cell
negative stain
dye/stain is absorbed into background
Simple stains
-Single stain
-emphasizes structures
Differential stain
-Differentiates organism based on stain interactions
-2+ stains
Gram stain
-Distinguishes different cell wall components
-Important clinical diagnostic tool
-steps include: Heat fix smear, primary stain with crystal violet, Mordant which is iodine, decolorizer which is alcohol and finally counterstain with safranin 
Gram-positive cell wall
Has a thick Peptidoglycogen which then means that it is able to absorb the crystal violet hence the turning of purple of gram-positive cells
Gram-negative cell walls
Has a thin peptidoglycan wall 
Acid fast stain
-Diagnostic tool for detection of my colic acid and mycobacterium spp.
-steps: heat fix smear, Primary stain (carbolfuschin), decolorizer, counter stain (methylene blue)
Capsule stain
-Diagnostic tool for detection of protective coating
-Dyes does not penetrate capsule
-steps: no heat smear, primary stain (india ink)
Endospore stain
-Identification of endospore formers
-schaeffer fulton method: Uses he to push the primary stain into the endospores 
-steps: heat fix smear, primary stain (malachite green), decolorizer (water), counter stain (safranin)
-Important for identifying bacillus and clostridium
Flagella stain
-Identification of flagella appendages
-bacteria, archaea, eukaryotes
-steps: No heat smear, primary stain (specialized), decolorizer (water), counterstain (carbol fuschin)
TEM
-Samples Annalise must have very thin sections
-Specimen embedded in plastic resin and dehydrated
-stained with electron dense heavy metals
SEM
-More dehydrated-critical point drying with liquid CO2
-Sputter coated with metal
