Quiz 1 Flashcards
basic components of microscope
resolving power
shortest distance two objects can be seen
numerical aperture
mathematical function; the higher the numerical aperture, the higher the resolving power
oil immersion
increase resolution & clarity of microscopic images; place 4 drops of oil at each corner near specimen
parfocal
ability to stay concentrated as the user switches objective lenses
calculation of the power
eye piece: 10x
objective lenses: 4x, 10x, 100x
multiply eye piece by objective lens
cell configuration
how cells are arranged
the microscope in microbiology: bacterias used
escherichia coli, staphylococcus epidermidis, bacillus subtilis
the microscope in microbiology: motility
cells must be viable & unstained; individual cells that are motile, travel many cell lengths in distances from each other
the microscope in microbiology: motility: what animal can we compare motility to?
tadpoles
the microscope in microbiology: are unstained bacteria easy to observe with the microscope and why? what cell configuration did you observe for each organism?
no because bacteria may be transparent and must be dyed to be visible
E. Coli: single straight rods
S. epidermidis: single spherical
B. subtilis: single rods, chains, and clusters
autochthonous
referring to a microorganism that is native to a location
allochthonous
referring to a microorganism that is not native to a site
aerobe
microorganism that needs oxygen for growth
anaerobe
microorganism that can thrive in environments without any oxygen
facultative anaerobe
a microorganism that can grow under aerobic or anaerobic conditions
methods for growing anaerobes
anaerobic chamber or glove box, anaerobic jar, roll tube, and thioglycate broth tube
testing the environment for microorganisms: methods used
air. armpit, throat sink
testing the environment for microorganisms: incubation conditions
place plate upside down; 37 degrees centigrade for 18-24 hours
testing the environment for microorganisms: post-incubation period
store at 4 degrees centigrade until the next week
testing the environment for microorganisms: sink results
hundreds of colonies; large, white, & clumped;
testing the environment for microorganisms: mouth results
hundreds of colonies; clear, tiny, spread apart
testing the environment for microorganisms: armpit results
few colonies; big colonies;
testing the environment for microorganisms: air results
fewest; large, clear
testing the environment for microorganisms: Why would the air not produce many colonies
microorganism don’t usually live in the air; it doesn’t have water or nutrients
testing the environment for microorganisms: T OR F: Anywhere there is moisture microorganisms can be found
True
testing the environment for microorganisms: microbes that are rare in nature
you won’t see all of the possible types; some may need specific pH, temperature, may need oxygen, nutrients (media), transportation errors/ process of collecting, and germs may grow too slowly.
testing the environment for microorganisms: did all the microorganisms get sampled during environment
no, there are many variations and differences in how microorganisms grow
colony
a large group of cells produced from one cell
pure culture
culture of only one strain
working under a flame
microbiologists work under the flame of a gas burner which provides an updraft so microbes in the air don’t fall inside materials such as tubes and plates
aeseptic technique and culture inoculation: bacteria used
escherichia coli
serratia marcescens
aeseptic technique and culture inoculation: 3 different methods
agar slant tube, nutrient agar plates, tubes of broth
aeseptic technique and culture inoculation: tubes of broth
mix a loopful of bacteria mix into broth tube
aeseptic technique and culture inoculation: agar slant tube
mix a loopful of bacteria and touch to the base starting at the lowest point of the slant and wiggle and draw it up from side to side to the highest point
aeseptic technique and culture inoculation: agar nutrient plate
important for pure culture; obtain loopful of S. marcescens and make a streak plate; incubate at room temperature
aeseptic technique and culture inoculation: growth
cloudy shows growth; clear means no growth
aeseptic technique and culture inoculation: Did all the colonies look identical?
No, there was variation in size and remember
aeseptic technique
method; keeps things free from being infected
mixed culture
variety of strains; opposite of pure culture
contaminant
substance that makes something impure
aeseptic technique and culture inoculation: how can something become contaminated
by not using aeseptic technique; not hand washing, not flaming loop, etc
stain or dye
organic compound with chromophore group (gives color) and auxochrome group (gives + or - charge)
basic dyes
crystal violet, safranin red, malachite green, and methylene blue; used in staining because cells have chemical groups with negative groups
What is the charge of crystal violet, safranin red, malachite green, and methylene blue?
positive
simple staining: bacteria used
bacillus subtilis
staphylococcus epidermidis
escherichia coli
simple staining
technique that uses only 1 stain
simple staining: what do you think is the purpose of heat-fixing bacteria to a slide for staining?
heat fixes so it does not wash off
differential staining
gram stain & acid-fast or ziehl-neelsen stain
structural staining
spore stain & flagella stain
cell biochemicals that effecting staining
peptidoglycan, lipids, and capsule polysaccharide
special staining technique: bacteria used
escherichia coli
staphylococcus epidermidis
bacillus subtilis (old culture)
klebsiella pneumonia
gram positive
purple
gram negative
red
T OR F: gram stain is also a “differential staining”
true
what are you staining in a negative stain
the background
What drug/bacteria is involved with differential (acid -fast) stain?
Escherichia Coli (S. epidermidis)
What drug/bacteria is involved with structural stain?
B. subtilis
What drug/bacteria is involved with negative?
Klebsiella
special staining: why do we heat fix spore cultures?
to kill the spore so we can see the malachite green
special staining: What is the purpose and nature of the acid-fast staining procedure which was not done in this lab session?
to stain bacteria with tough waxy cell walls
acid-fast staining process
stain slide with carbon-fuschsin (red) which is retained by acid-fast bacteria, then treated with decolonized (acid alcohol) washing out red stain , then counter-stained with methylene blue and stains non-acid-fast. Acid alcohol - can’t wash out wax wall (tough).
Allows to distinguish between acid-fast and non-acid fast bacteria
autoclaving
steam under pressure in chamber (121 centrigrade, 15 lb/in^2, 15 minutes minimum) will destroy ALL microbes
pasteurization
heating in a water bath at 63 centrigrade for 30 minutes and destroys MOST pathogens
dry heat
baking 160-180 centigrade for 1-2 hours will destroy ALL microbes
filtration
sterile nitrocellulose filters w .45 um pores are good to remove cells from heat sensitive liquids
UV light
UV lamps are frequently used to disinfect laboratory surfaces
ultrasound
high frequency sound is used in machines to clean instruments or break cells, do not sterilize
Common Physical Agents: bacteria used
E. coli
Common Physical Agents: methods of sanitation/sterilization
control, sonication, and autoclaving
What is the most effective method of microbe destruction?
Autoclaving
Common Physical Agents: incubation method
37 degrees centigrade overnight
Common Physical Agents: results of physical agents
control: +, showed growth
sonication: +, showed growth
autoclaving: -, did not show growth
Common Physical Agents: What types of radiation besides UV light can be used to kill bacteria?
autoclaving, pasteurization, dry heat, filtration, & ultrasound
disinfectants
phenols, chlorine, and glutaraldehyde
antiseptics
ethanol and isopropanol
chemical used for sterilization
ethylene oxide gas
chemicals that remove/stop microorganisms
soaps & detergents
Common Chemical Agents: bacteria used
e. coli
What disinfectant are you able to use on the skin?
antiseptic
common chemical agents: what do you conclude about the relative effectiveness of the chemical agents you tested
soap: nothing
NaCl: nothing
Ethanol: slight effect
Bleach: killed all microorganisms
colony count
samples of diluted culture are spread over surfaces of agar in petri plates. After incubation the # of colonies can be used to calculate cell concentration
petroff-hausser counter
engraved grid on microscope slide is used for counting cells in a known volume
spectrophotometer
cell concentration can be determined in this device by measuring the light absorbed
coulter counter
cell # and size can be determined in this machine which measures electrical resistance
cell mass
dry or wet weight gives an estimate of the number of cells
metabolic methods
oxygen consumed or carbon dioxide produced can indicate microbial growth
Cell Concentration Assay: colony count method: bacteria used
E. coli
What is the ideal amount of colonies in cell concentration assay?
30-300 colonies
What is the limit to the concentration?
10^7; maybe 10^9
Cell Concentration Assay: does this assay method detect every cell body spread on a plate and why?
Some could be dead (many generations of bacteria)
If there is a cluster of different bacteria —> will only make one type of colony (can get lost here)
Cell Concentration Assay: methods quicker than cell concentration assay
Petroff-Hausser counter, coulter counter, spectrophotometer
Simple Stain Unknown
Bacillus
Negative: Red
Singles, Pairs, Cluster
