WSU Lab Exam

Microorganism
any living organism that must be examined with a microscope
Ocular
Magnifying lens usually 10X
Body Tube
mirrors/prisms to make image
Objective lens
magnify the speciment (10X, 40X, 100X)
Stage
platform that holds slide
Mechanical Stage
allows slide to be moved on the stage
Coarse Knob
focuses in 10X and 40X
Fine Knob
Focuses in on small things
Condenser
focus light on stage
Iris Diapgragm
controls amount of light able to enter
Light Source
provides illumination
Aseptic
free of contamination
Contaminants
unwanted organisms
bacterial smears
preparations of cultures using thin smear of culture
simple stain
easy to distinguish organisms and background, positive charge and attracted to negative charged bacteria
morphology
shape
Coccus
round shaped
bacillus
rod shaped
heat fixed
act of drying out bacteria so the cells will stay in place for staining
negative stain
used in seeing size/shape by not using harsh dyes or heat that could distort organism. Congo red and nigrosin have negative charges and are repelled by the negatively charged bacteria. cells are left unstained, background is stained
Differential stains
allows ppl to see difference between organisms or parts of the same organism
Primary Stain
stains all cells
decolorizing
removes stain from certain types of cells
counterstain
stains cells that have lost the color of the primary stain
Gram positive
cell walls have thick peptidogylcan layer. Stained Purple
Gram negative
cell walls have thin peptidoglycan layer as well as LPS layer. Stained Red.
Gram Stain
Smear is heat fixed. Flood with crystal violet. Rinse slide with water. Flood with gram’s iodine. Rinse with water. Decolorize with ethanol acetone soln. Rinse with water. Flood with safranin. Rinse with water. Blot with bibulous paper. Examine under oil immersion.
Mordant
enhances crystal violet stain on gram positive cells.
Capsule
layer surrounding and attached to cell wall made of proteins. Prevents drying of organism, helps organism hide from immune system, traps other plaque.
Capsule Stain
Congo red is applied to slide, culture is mixed in, prepare a thin smear, let air dry, flood with AM capsule stain, rinse with deionized water, examine under oil immersion. Stain with be red cell with clear zone (capsule) with stained background.
Endospore
formed in environmental stress and keep the dna safe to “start” back up again
Germinate
endospores go to vegetative cells to start again
vegetative cells
makes pathogen when environmental conditions are met
spore coat
tought outer layer that is not readily stained so must have extreme conditions to drive stain into spore
free endospore
not in a vegetative cell
subterminal endospore
located inside cell to the left
central endospore
located inside in the middle of cell
terminal endospore
located inside to the right of cell
endospore stain
heat fix a smear, place on can of boiling water with extreme heat, flood smear with malachite green, keep slide from drying out, rinse with water, flood with safranin, rinse with water, dry and examine under oil immersion
pure culture
only a single microbial species
streak plates
culture is streaked out over agar plate to spread out culture until isolated colonies are obtained.
pour plate
bacteria is mixed in a tube of melted agar, mixed and poured into petri plate
Colony Forming Units
CFU, isolated colonies on surface
loop dilution
mixing culture into melted agar, until CFUs are obtained
Microbiological media
food required for organisms to grow
liquid media
broth, tubes, etc used to grow large numbers of bacteria
solid media
prepared by adding solidifying agent to liquid medium
semi-solid media
adds solidifying agent but a less concentration so its jelly-like
non-synthetic media
complex components whose chemical makeup is unknown
synthetic media
purified and defined components
enriched media
media that have added nutrients
fastidious
picky-eaters
selective media
favor the growth of particular media
differential media
complex media but contain substances like ph indicator
autoclaving sterilization
application of moist heat and pressure
dry-heat sterilization
put in oven and exposed to high temps to prevent condensation
UV radiation
used on surface to kill bacteria using UV lights
ethylene oxide
gas used to sterilize items that are susceptible to high temps
filtration
physical removal of largeish bacteria using filter
Motility
ableness to move
Obligate aerobes
require oxygen
microaerophiles
require limited amount of oxygen, require levels of CO2
aerotolerant
grow well with or w/o oxygen
facultative anaerobes
grow in aerobic or anaerobic but grow better with oxygen
obligate anaerobes
die in presence of oxygen
reducing media
combination to reduce oxygen
Acidophiles
grow in acidic environments with pH below 5.5
Neutrophiles
grow in pH 5.5-8.6
Alkalinophiles
grow in pH 8.7-12
Psychrophiles
grow best at low temps -5 degrees-20 degrees celsius
Mesophiless
grow best at 20 degrees to 45 degrees
thermophiles
grow above 45 degrees celsius
minimal, optimal, maximum
lowest temp, ideal temp, highest temp for growth
Osmotic pressure
force which moves water from a low conc to a high conc
solute
substance dissolved in a soln
solvent
liquid to dissolve solute
hypotonic
low water conc so cell gets water and bursts
isotonic
equilibrium inside vs outside cell
hypertonic
high water conc, so cell releases water and cell collapses
osmophiles
grow in high conc
xerophiles
grow in dry
halophiles
grow in high concentrations
Biochemical Fingerprint
sum of metabolic activities of an organism’s enzymes
amylase
enzyme that breaks down glucose into single units to be used as energy
caseinase
breaks down casein into soluble units
hydrolyses
breaks down
DNA
gives organisms their unique characteristics
Plaque
hole created by single virus invading single host cell
bacteriophage
virus that only infect bacteria
Opportunistic Infections
infections caused by pathogens that take advantages of certain situations. Dont cause disease in host
viridans group
most common type of organism in blood
transient bacteremia
localized infections that are non-multiplying
sub-acute bacterial endocarditis
inflammation of the lining of heart valves
continuous bacteremia
bacteria constantly fed into the blood stream
septicemia
bacteremia gone bad that result in serious infection where organisms are actively growing in the blood
dental caries
cavaties that form when bacteria ferment carbs on the tooths surface
alpha hemolysis
destruction of RBC that form greenish area
Beta hemolysis
destruction of RBC that leaves clear zone
Gamma hemolysis
no effect on RBC, dont produce hemolysins
transmission
spread of disease
direct contact
person to person via cough, touching, air etc
fomites
spread via inanimate objects
vectors
spread via insect bites, etc
endemic
infectious disease constantly present in population
pandemic
pathogen causing disease throughout world
index case
first reported case during outbreak
reservoir
continuous source on infection
healthy carriers
organisms spreading disease without showing any signs or symptoms
pathogen
disease-causing organism
broad spectrum antibiotics
treat infections by killing gram + and gram – bacteria
Narrow spectrum antibiotics
very specific for one group of microorganisms
antiseptics
nonselective in their action, applied to skin commonly
disinfectants
nonselective in action, applied to objects like floors, tables
sanitizers
kills vegetative cells, used in food industry

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