Tools of the Labratory Flashcards
inoculation
introducing microbes to a fresh medium
incubation
placing microbes into optimal conditions (temperature, pressure, humidity)
what is the significance of 37C?
reflects body temperature; culture human pathogens/microbes
isolation
separating species form the rest of the sample
purpose of isolation techniques
achieve/obtain a single colony growing on a solid medium
single colony
spot on a plate; single clump of microbes that are clones of each other
Fanny Eilshemius Hesse
recommended the use of agar when studying microbes
streaking for singles
sectioning areas of microbes and reducing the amount of colonies to make single colonies
loop dilution
get sample (liquid/solid), collect on loop, and put into first culture onto sterile warm liquid agar → then placed into petri plate
loop dilution characteristics
- microbes embedded into agar (good for anaerobic microbes)
- can be diluted in agar solutions to single out colonies
spread plate
uses petri plates (liquid sample); spread culture evenly on plate and can be diluted in multiple tests
colony forming unit (CFU)
roughly equivalent to a cell; assume that one colony = one cell
broth v agar medium
broth: liquid
agar: solid
general-purpose media
medium which will grow most microbes; usually non-synthetic
synthetic medium
every molecule and the composition of the media is known
enriched media
any type of medium which is used for fastidious microbes (picky microbes)
selective media
overlaps with synthetic, some microbes are allowed to grow and divide while other are inhibited from growth
differential media
grows everything but shows the difference between each of the microbes
- Carry different characteristics under the media (colors, spread, etc)
pure culture
one known species of microbe
mixed culture
two microbes which are distinguishable from each other growing on the same media
contamination
growth of a microbe which is unwanted
viable but not culturable (VBNC)
living microbes that will not grow in the lab
- makes up for 90% of microbes
compound microscope
combines 2 different magnifying lenses/curved glasses
objective lens
where the light on a microscope passes through
ocular lens/eyepiece lens
increases magnification; where you view image
condenser lens
focuses the light source onto the specimen; underneath specimen, above the lamp
magnification
result of light waves passing through curved glasses/lenses which then refracts light increasing the image of the organisms that you are viewing
increasing the curvature of the lens…
increases the magnification
resolution
the ABILITY to see two objects as being separate
what is the physical limiting factor the keeps light microscopes from visualizing smaller objects?
resolution; harder to obtain smaller wavelengths which is optimal for better resolution of an object
limit of resolution
the DISTANCE two objects need to be to be seen as separate
how to calculate limit of resolution?
wavelength of light (nm) / NA condenser + NA of objective lens
NA
numerical aperture of lens; 200 µm
what is the oil immersion lens used for?
to view smaller bacteria and cells
what is the purpose of the oil with the 100x lens?
the oil bends/refracts light that would escape to go into the objective lens; retains more of the light moving through the specimen
properties of the oil
the oil must have the same refractive properties of glass
bright field microscope
most commonly used to view dead cells; field is brighter than the specimen
dark field microscope
used to see living specimens (possibly swimming around); field is darker than the specimen
what does the dark field microscope highlight?
shines only the exterior of the cell and their general characteristics; does not include the internal structures of the cell
use of differential interference contrast (DIC) & phase-contrast microscope
view internal structures of living cells
difference between DIC and phase-contrast microscope
each have the ability to view different structures in a cell; use depends on what structure of the cell you are trying to view
hanging drop slide
good for large moving organisms
electron microscope
electrons go through magnets to increase the size of the image instead of the lens
what stain is used for electron microscopes?
specimen is coated in metal particles due to the electrons being able to move through metal easier
what do electron microscopes use to help visualize a specimen?
electrons go through magnets to increase the size of the image
TEM
transfer electrons through the specimen; electrons come from underneath and through to view internal structure of the cell
- specimen must be cut in half
SEM
electrons go on top on the surface and they bound off of the microbe to visualize the surface of the cells; scanning over the surface of the cell
when are SEM and TEM used?
only used for research
Which microscope does not use light in forming the specimen image?
electron microscope
Which of the following characteristics refers to the microscope’s ability to show two separate entities as separate and distinct?
resolving power
A medium is designed that allows only staphylococci to grow. In addition, S. aureus colonies have a yellow halo around them and other staphylococci appear white. This type of media is…
both selective and differential
A common medium used for growing fastidious bacteria is…
chocolate agar
The Gram stain, acid-fast stain, and endospore stain are…
differential stains
Which method often results in colonies developing down throughout the agar and some colonies on the surface?
pour plate
Which microscope shows cells against a bright background and the intracellular structures of unstained cells based on their varying densities?
phase contrast
If a microbiologist is studying a specimen at a total magnification of 950X, what is the magnifying power of the objective lens if the ocular lens is 10X?
95X
A nutrient medium that has all of its chemical components identified and their precise concentrations known and reproducible would be termed
synthetic
