Microbio Lab Exam 1

E. Coli is which of the following:

gram positive or gram negative

gram negative

staphylococcus epidermidis is which of the following:

gram negative or gram positive

gram positive

After gram staining, what color will E. Coli be?

pink or red

After Gram staining staphylococcus epidermidis should appear what color?

purple

what is the primary stain in gram staining?

crystal violet

Which types of bacteria form endospores?

clostridium and bacillus

what is the primary stain in endospore staining?

carbolfuchsin

why are bacteria placed in boiling water during endospore staining?

it allows the primary stain to seep into bacterial cell wall

why is nigrosin used during endospore staining?

it stains the background for contrast

what color will the endospore be after staining using the Dorner method?

Red spores with a green vegetative cell

if a bacteria has an extra cellular gel like layer that is distinct and gelatinous, It is a what?

Capsule

what is the primary stain in capsular staining?

1% crystal violet

during capsular staining, which of the following is true:

Heat fixing is important to make the bacteria stationary on the slide

heat fixing is not done because it can damage the capsule

heat fixing is not done because it can damage the capsule

what is 20% copper sulfate used in capsular staining as?

A decolorizer and counter stain

which is true after capsular staining:

cells appear dark purple with a clear halo around them

Cells appear clear with a dark purple halo around them

cells appear dark purple with a clear halo around them

why is acid-fast staining needed for some organisms?

The gram stain will not work because these organisms have mycolic acids in their cell wall

which bacterium has mycolic acid in it’s cell wall?

staphylococcus epidermis

E. coli

Mycobacterium smegmatis

Mycobacterium smegmatis

what is the primary stain in acid-fast staining?

DMSO

what is the counterstain in acid-fast staining?

methylene blue

making a heat fixed smear is unnecessary for acid-fast staining true or false

false

when putting a microscope away, what objective lens should be in place?

scanning

The ocular lens has a magnification of what?

10X

if the objective lens in place is 40X, what is the total magnification of the specimen?

400X

what is the maximum number of microscopes that should be carried at one time?

One

True or false:

Microscopes can be cleaned with paper towel

False

in order to move the stage up and down in large movements, what should one use?

The course adjustment knob

in order to move the stage up and down using smaller movements what should one use?

The fine adjustment now

immersion oil should be used for which objective lens

100X

immersion oil should be wiped off using

Lens paper

in order to view live specimens in (for example) pond water, one should use

Wet mount

what procedure is required for aseptic technique?

step 1. cap is removed from sterile broth (whatever you are putting bacteria into) and tube mouth is flamed

step 2. loop with culture sample is inserted into tube of sterile broth

step 3. loop is removed from broth and tube mouth is flamed

step 4. tube cap is returned to tube

step 5. loop is flamed and returned to receptacle

what is the purpose of thioglycolate media?

to see which organisms can survive in low oxygen concentrations (which organisms are anaerobic)

what is the purpose of a serial dilution?

to make the bacteria less concentrated

what are the 4 different streaks we did in lab?

quadrant, T-streak, continuous, and radiant streaking

what is the diaphragm of the microscope responsible for?

regulates the amount of light that reaches the slide

what is the condenser of the microscope responsible for?

collecting and directing light from the light source to the slide

what 2 organisms did we perform the gram stain on? and what were the outcomes?

e. coli (negative/ pink)

staphlococcyx epidermidis (positive/purple)

which organism did the thioglycolate media show lives best in environments with low oxygen levels?

clostridium sporogenes

what is the purpose of staining?

to enhance cell features and structures so the bacterial cell can be visualized with a brightfield microscope

what is a primary stain?

commonly used dyes that have color-bearing ionic groups (chromophores)

why is aseptic technique important?

it ensures that no contaminating organisms are introduced into culture materials while handling and none are contaminating the handler or others

when do we use immersion oil?

between the slide and the 100X objective lens.

why do we use immersion oil?

the oil forms a continuous lens system that limits the loss of light due to refraction

what are the steps in making a smear from broth cultures (liquid)?

1. 2 loopfuls of liquid containing organisms are placed in the center of the “target circle”

2. organisms are dispersed over entire area of “target circle”

3. the smear air dries at room temp for 5 mins

4. slide is passed through flame several times to heat kill and fix organisms to slide

what are the steps in making a smear from plates/slants?

step 1. two loopfuls of water are placed in the center of the target circle

step 2. a very small amount of organisms is dispersed with inoculating loop in water over entire area of the target circle

step 3. the smear air dries at room temp for 5 mins

step 4. slide is passed through flame several times to heat kill and fix organisms to slide

what are the steps of simple staining?

what are the steps of endospore staining

what are the steps of acid-fast staining?

what are the steps of capsular staining?

what are the steps of gram staining?

what are the reagents of simple staining

what are the reagents of endospore staining?

what are the reagents of acid-fast staining?

what are the reagents of capsular staining?

what are the reagents of gram staining?

what is the final result if simple staining?

what is the final result of endospore staining?

what is the final result of acid-fast staining?

what is the final result of capsular staining

what is the final result of gram staining?

what are the 3 different bacterial morphologies

rods (coccobacillus, bacillus and fusiform), spherical (coccus) and spiral/curved (vibrio, sprillum, spirochete)

what would (coccobacillus) look like under a microscope?

what would (bacillus) look like under a microscope?

what would (fusiform) look like under a microscope?

what would (coccus) look like under a microscope?

what would (spirochete) look like under a microscope?

what would (spirillum) look like under a microscope?

how do you calculate the original concentration of bacteria after serial dilation?

rate of dilation x # of colonies

what is the proper way to handle agar plates?

what 2 organisms are involved in the gram stain we did in lab?

E. Coli

Staphlococcyx Epidermidis

what 2 organisms are involved in the acid-fast stain we did in lab

mycobacterium and staphlococcyx epidermidis

what organism is involved in the endospore stain we did in lab

bacillus cereus

what organism is involved in the capsule stain we did in lab?

enterobacter aerogenes

what bacteria was best at growing at high temperatures in the lab?

geo bacillus

what bacteria was best at growing at high salt concentrations in the lab?

halobacterium salinarum

what are do the following results of thioglycolate media imply?

No turbidity

no growth of organisms

what are do the following results of thioglycolate media imply?

Growth near the top, but not on the surface

what are do the following results of thioglycolate media imply?

Even growth throughout

what are do the following results of thioglycolate media imply?

Dense growth at the top, with turbidity throughout

what are do the following results of thioglycolate media imply?

Growth only at the bottom

what are do the following results of thioglycolate media imply?

Growth only at the top