Microbiology Lab Final Exam Quizlet
List 4 types of media - ANSWER...-broths, agar slants, agar deeps, agar plates
What are broths useful for? - ANSWER...-For growing large amounts of bacteria
What are slants and plates useful for? - ANSWER...-For growing a selective,
concentrated number fo bacteria
What are agar deeps for? - ANSWER...-For bacteria that do not require as much
oxygen
What are agar plates used for? - ANSWER...-For determining colonies and purity of a
culture sample
List 3 ways to incorrectly inoculate a broth - ANSWER...--didn't check culture for
contamination before you started
-didn't sterilize the loop before transferring the bacteria. You have to let the loop cool too
before you can use it.
-leave the agar plates or tubes open
Where should you dispose of sharps? - ANSWER...-Dispose of biohazard sharps in
hard containers, and plates in yellow plastic bags.
What is an autoclave and why do we use autoclave tape? - ANSWER...-An autoclave is
a strong heated container used for chemical reactions and other processes using high
pressures and temperatures. Autoclave tape is used to tell if a tip box has been
sterilized or not.
When viewing a slide at 100X, what steps do you take from start to finish? -
ANSWER...-1. go get the microscope, remove the dust cover, and carry it with 2 hands
to the bench
2. Take your slide and clamp it into place. Then put down the 10 X objective.
3. slowly raise the stage, but don't let the stage hit the objectives. Once you focus in 10
X, swap to 40 X. Then, you can increase the light source.
4. fine focus the 40 X using the knobs.
5. Before you switch to 100 X, half way between 40 and 100 X, put a small drop of
immersion oil on the center of the slide, then click the 100 X objective into place. Use
the fine focus, but go slowly.
6. Once you're done examining your sample, lower the stage, remove the slide, and
wipe off the immersion oil using a chem-wipe. Put the slide back or dispose of it
according to what your project is.
, 7. unplug it, wrap the cord around the arm, replace the dust cover, carry it back to the
cabinet with two hands.
What methods are used to view the exterior cell structure? - ANSWER...-Gram stain
explain the gram stain process - ANSWER...-1. take thin slide, heat fix.
2. crystal violet, 1 minute, stains exterior of G+ and G- bacteria. Rinse off crystal violet.
G- has LPS, G+ has peptidoglycan layer.
3. iodine to fix the crystal violet.
4. Add ethanol for 30 seconds or so. Just until the run off is no longer purple. destroying
membrane of G-.
5. counterstain with safranin for a minute.
Gram negative is what color? - ANSWER...-pink
gram positive is what color - ANSWER...-purple
What happens if you forget to heat fix? - ANSWER...-Your sample washes off the slide
What happens if you made your smear too thick? - ANSWER...-Ethanol can't shred the
outer layer of membrane so it will all look purple.
What happens if you forget to add iodine to a gram stain? - ANSWER...-The iodine fixes
the crystal violet into place. If you forget it, you'll wash the crystal violet off. You might
not get to see anything or everything will look G+ with the counterstain.
What happens if you forget to add ethanol to a gram stain? - ANSWER...-The ethanol
shreds the outer layer. It's what makes the difference between G- and G+. Everything
will look G+ (all purple). You won't get rid of G- membrane so counterstain won't work.
What happens if you forget safranin in a gram stain? - ANSWER...-Safranin is the
counterstain. Without it, you can't see the G- bacteria. Sample looks clear or empty.
What's the purpose of a streak plate? - ANSWER...-To get a pure culture, to isolate
colonies
What are two criteria of a streak plate to determine if you've succeeded? - ANSWER...-
1. the sample is going down in dilution factor each time, so you should see the amount
of confluent growth go down as well until you reach distinct colonies.
2. you only see one type of bacteria in a plate.
How do you label an agar plate? - ANSWER...-Once the plates are dried of any
condensation, the plates are labeled along the edge because what we're examining
goes in the middle.
List 4 types of media - ANSWER...-broths, agar slants, agar deeps, agar plates
What are broths useful for? - ANSWER...-For growing large amounts of bacteria
What are slants and plates useful for? - ANSWER...-For growing a selective,
concentrated number fo bacteria
What are agar deeps for? - ANSWER...-For bacteria that do not require as much
oxygen
What are agar plates used for? - ANSWER...-For determining colonies and purity of a
culture sample
List 3 ways to incorrectly inoculate a broth - ANSWER...--didn't check culture for
contamination before you started
-didn't sterilize the loop before transferring the bacteria. You have to let the loop cool too
before you can use it.
-leave the agar plates or tubes open
Where should you dispose of sharps? - ANSWER...-Dispose of biohazard sharps in
hard containers, and plates in yellow plastic bags.
What is an autoclave and why do we use autoclave tape? - ANSWER...-An autoclave is
a strong heated container used for chemical reactions and other processes using high
pressures and temperatures. Autoclave tape is used to tell if a tip box has been
sterilized or not.
When viewing a slide at 100X, what steps do you take from start to finish? -
ANSWER...-1. go get the microscope, remove the dust cover, and carry it with 2 hands
to the bench
2. Take your slide and clamp it into place. Then put down the 10 X objective.
3. slowly raise the stage, but don't let the stage hit the objectives. Once you focus in 10
X, swap to 40 X. Then, you can increase the light source.
4. fine focus the 40 X using the knobs.
5. Before you switch to 100 X, half way between 40 and 100 X, put a small drop of
immersion oil on the center of the slide, then click the 100 X objective into place. Use
the fine focus, but go slowly.
6. Once you're done examining your sample, lower the stage, remove the slide, and
wipe off the immersion oil using a chem-wipe. Put the slide back or dispose of it
according to what your project is.
, 7. unplug it, wrap the cord around the arm, replace the dust cover, carry it back to the
cabinet with two hands.
What methods are used to view the exterior cell structure? - ANSWER...-Gram stain
explain the gram stain process - ANSWER...-1. take thin slide, heat fix.
2. crystal violet, 1 minute, stains exterior of G+ and G- bacteria. Rinse off crystal violet.
G- has LPS, G+ has peptidoglycan layer.
3. iodine to fix the crystal violet.
4. Add ethanol for 30 seconds or so. Just until the run off is no longer purple. destroying
membrane of G-.
5. counterstain with safranin for a minute.
Gram negative is what color? - ANSWER...-pink
gram positive is what color - ANSWER...-purple
What happens if you forget to heat fix? - ANSWER...-Your sample washes off the slide
What happens if you made your smear too thick? - ANSWER...-Ethanol can't shred the
outer layer of membrane so it will all look purple.
What happens if you forget to add iodine to a gram stain? - ANSWER...-The iodine fixes
the crystal violet into place. If you forget it, you'll wash the crystal violet off. You might
not get to see anything or everything will look G+ with the counterstain.
What happens if you forget to add ethanol to a gram stain? - ANSWER...-The ethanol
shreds the outer layer. It's what makes the difference between G- and G+. Everything
will look G+ (all purple). You won't get rid of G- membrane so counterstain won't work.
What happens if you forget safranin in a gram stain? - ANSWER...-Safranin is the
counterstain. Without it, you can't see the G- bacteria. Sample looks clear or empty.
What's the purpose of a streak plate? - ANSWER...-To get a pure culture, to isolate
colonies
What are two criteria of a streak plate to determine if you've succeeded? - ANSWER...-
1. the sample is going down in dilution factor each time, so you should see the amount
of confluent growth go down as well until you reach distinct colonies.
2. you only see one type of bacteria in a plate.
How do you label an agar plate? - ANSWER...-Once the plates are dried of any
condensation, the plates are labeled along the edge because what we're examining
goes in the middle.
