Lab 1 Flashcards
What is the highest total magnification possible for the microscope you will be using in lab?
1000X
To calculate the highest total magnification possible, multiply the magnification of the ocular lens (10X) times the magnification of the highest objective lens (100X).
One objective lens on the compound light microscope MUST always be used with immersion oil. It is also the ONLY one that can be used with immersion oil. The magnification of this objective lens is
100X
The other lenses are not sealed against the immersion oil and can be damaged if oil is used with them. If you accidentally get oil on one of these lenses, clean it off immediately with gauze and lens cleaner.
Which of the following slides will you view as part of this lab exercise?
1) dry mount of magazine photo
2) prepared slide of bacteria
3) Wet mount of living unstained microbes
4) all of the above
4) all of the above
Start with the magazine photo since you will likely find it easiest to focus on this specimen.
Which one of the following slides will you view using the 100X oil immersion lens?
1) dry mount of magazine photo
2) prepared slide of bacteria
3) wet mount of hay infusion
4) all of the above
2) prepared slide of bacteria
Because bacteria are so small, the oil immersion lens is necessary to view them well. Many of the organisms you will see in the hay infusion are eukaryotic and are easily viewed with just the 40X objective lens.
Where should you dispose of gauze used to clean immersion oil off of your microscope?
1) regular trash can
2) red biohazard bucket on lab bench
3) white biohazard bucket in front of lab
4) take it home with you
1) regular trash can
Uncontaminated waste like the gauze and also the paper-towels used to clean your lab bench should go into the regular trash.
When you finish using the microscope, what should you have your lab instructor do?
1) clean the scope
2) collect any slides you prepared during the lab
3) inspect your drawings of bacteria
4) inspect the microscope
4) inspect the microscope
Always have your lab instructor check the scope to make sure it has been cleaned properly.
You will label the bottom of the plate you streak with an environmental sample before you incubate the plate. Which one of the following information below should not be included on the plate?
1) your name (or initials)
2) your TA’s name
3) date
4) name of the medium used
5) source of the sample
2) your TA’s name
Be sure to label the bottom of the plate around the edge as described in Exercise 3 of your lab manual.
You will find a wax pencil in your supply cabinet, but you will need to bring your own “Sharpie-type” marker. Which one should you use to label your plate?
1) wax pencil
2) Sharpie marker
2) Sharpie marker
The Sharpie marker will be used to label plates and tubes of media. You will use the wax pencil to label slides.
You will use a sterile swab to inoculate your plate during this exercise. Where should you dispose of the swab and the wrapper?
1) both in the regular trash
2) both in the red biohazard bucket
3) swab in the red biohazard bucket and wrapper in the regular trash
4) swab in the red biohazard bucket and wrapper in the white biohazard bucket
3) swab in the red biohazard bucket and wrapper in the regular trash
Your lab section will have a plastic box marked with your TA’s name and the incubation temperature in which to place any plates for incubation.
In order to prevent excess condensation from dropping onto the surface of your plate, how should your plate be oriented when you place it in the box?
1) top up (labeled bottom side down)
2) inverted (labeled bottom side up)
3) placed into holder so they are vertically oriented
4) wrapped in a paper towel right side up
2) inverted (labeled bottom side up)
If condensation drops onto the surface of the plate, it can cause the colonies growing on the plate to run together and you will not be able to identify them properly.
Where should you dispose of paper towels used to clean your bench at the end of the lab
1) Regular trash cans
2) Red biohazard bucket on bench
3) White biohazard bins on disposal cart
1) Regular trash cans
When you go to inoculate your TSA plate what should you do with the lid of the plate?
1) Take the lid completely off the plate and sit it on the bench top next to the plate while you streak
2) Have your lab partner hold the lid of the plate for you while you streak
3) Partially open the lid of the plate and continue to hold it in your hand while you streak
4) All of the above are acceptable
3) Partially open the lid of the plate and continue to hold it in your hand while you streak
microbiology
the study of microscopic organisms, or microbes, that are below the limit of vision of the human eye (which is about 200 µm)
objective lens
the lens closest to the objector specimen
ocular/eyepiece lens
the lens closest to your eye
total magnification
determined by multiplying the magnifications produced by the objective lens and the ocular lens
resolving power
the ability to distinguish two closely spaced points or objects as separate
numerical aperture
a physical quality of the lens; a measure of its ability to gather light
parfocal microscope
remains in focus as it switches from objective to objective
motility
the ability of an organism to propel itself through its environment
if a bacterial organism appears to simply be vibrating in place, this is not motility, but rather a phenomenon known as ________
Brownian motion
Brownian motion is caused by
the random collisions of particles and/or the cells in the suspension
current flow
everything on the slide moves in the same direction at once; commonly occurs as a slide begins to dry out
dark-field microscope
produces bright images of specimens against a dark background or field
dark-field microscope typically used to view _____, and in order to determine their ____
- viable (living), unstained organisms
2. morphology and motility
phase contrast microscope useful for
determining microbial motility and morphology; to visualize certain cellular structures and inclusions that generally cannot be seen clearly under standard bright-field or dark-field microscopes
fluorochromes
chemicals that produce fluorescence after they absorb a specific wavelength of light
used alone, fluorochromes can be described as a
differential dye
immunofluorescence microscopy
fluorochrome is attached to an antibody that binds to specific cellular components
transmission electron microscope
electrons are passed through a very thin section of a specimen that has been stained with an electron-dense metal
immunoelectron microscopy (variation on TEM)
uses TEM but allows for visualization of specific cellular components through the use of antibody pairs
scanning electron microscope
used to visualize the surfaces of objects, and the final image produced is 3-D
autotrophic
capable of producing their own “food”/nutrients from inorganic carbon and energy sources
heterotrophic
dependent on sources from their environment to provide the nutrients
photoheterotrophic
fall between autotrophs and heterotrophs
aerobes
require oxygen to survive
aerotolerant
aerobes that only tolerate low oxygen concentrations
anaerobe
may be killed if exposed to oxygen
facultative anaerobe
function either with or without oxygen
serial dilution
when the suspension must be diluted several times in succession
formula for cfu/mL calculation
(# cfu) / (volume plated [mL] x total dilution used [no unit])
if two plates made from different dilutions in a series have produced colony counts in the 30-300 range, then
the calculated original concentrations obtained from each of these counts can be averaged
working with grams instead of mL
1 gram of any substance is arbitrarily assigned a volume of 1 milliliter
