material before midterm

Question 1

Parts of microscope

Stage

Answer 1

flat mechanical surface where the slide is placed on

Question 2

Parts of microscope

Ocular lenses

Answer 2

magnify the specimen

Question 3

Parts of microscope

Coarse focus

Answer 3

moves stage vertically; toward; and away from the objective lens

Question 4

Parts of microscope

Fine focus

Answer 4

moves stage up and down but in smaller increments

Question 5

Parts of microscope

Condenser

Answer 5

focuses light

Question 6

Parts of microscope

Iris diaphragm

Answer 6

can be opened and closed to control amount of light that passes through

Question 7

Parts of microscope

objective lenses

Answer 7

4X
10X
40X
100X

Question 8

safety rules, proper care of the microscope

(cleaning and putting away)

Answer 8

wipe the objective with lens paper; blot immersion oil off

remove slides

put the stage all the way down

move objective back to 4X

Question 9

how to calculate Total Magnification (TM)

Answer 9

ocular lens x objective lens

Question 10

cellular morphologies

cocci

Answer 10

spheres, spirals

Question 11

cellular morphologies

bacilli

Answer 11

rod-shaped

Question 12

cellular arrangements

strepto

Answer 12

chains

Question 13

cellular arrangements

staphylo

Answer 13

clusters

Question 14

cellular arrangements

diplo

Answer 14

groups of 2

Question 15

slide smear

Answer 15

from aseptically spreading bacteria from broth pr from plate to heat fixation

label slide

sterilize loop

for B. subtilis on soild media place 1-2 loopfuls of distilled water in the center of one circle on the slide

re-flame loop

cool loop

scrape a small amount of culture from the surface of the agar

sterilize loop

let smear air dry

once air dried heat fix 2-3 times

now smear is ready for staining

Question 16

gram stain

Answer 16

1)
step: primary stain
reagent: crystal violet
time: 1 min
gram +: purple
gram -: purple

2)
step: mordant
reagent: iodine
time: 1 min
gram +: purple
gram -: purple

3)
step: decolorizer
reagent: 95% ethanol
time: 15 sec
gram +: purple
gram -: colorless

4)
step: counterstain
reagent: safrinin
time: 2 min
gram +: purple
gram -: red/ pink

Question 17

If crystal violet is added second,

Answer 17

gram + will appear purple

Question 18

If iodine is applied first,

Answer 18

a gram + cell will not have gain any color

Question 19

Without the mordant being added after the crystal violet has already been applied, the CV-I complex will not form, and Gram-positive cells will not retain the purple stain when the decolorization is performed. Thus, if the

Answer 19

Thus, if the
iodine is added first and crystal violet second, Gram-positive cells will end up red/pink after steps
three and four are performed

Question 20

streak plating purpose

Answer 20

obtain isolated colonies of bacteria each of which represents a pure culture that multiplied from a single cell

Question 21

streak plate protocol

Answer 21

1) label bottom of agar plate with name, lab section, date, source of inoculum

2) flame loop until it turns red allow it to cool and aseptically obtain a loopful of broth culture labeled unknown mixture 8

3) lift one edge of the petri plate cover and streak 1st sector by making as many streak without overlapping previous streaks.

4) flame loop and let it cool, turn plate, streak 2nd quadrant

5) flame loop and let it cool, turn plate, streak 3rd quadrant

6) flame loop, let it cool, turn plate, streak 4th quadrant

7) incubate the plated in an inverted position at 37 degrees Celsius, isolated colonies develop (24-48 hrs)

Question 22

how to properly label a streak plate and put plates away for incubation

Answer 22

agar side up label
name, date, teacher, name of bacteria

agar up in tub for incubation

Question 23

starch agar looks like what

Answer 23

non selective media that contain starch

B. subtilis only bacteria that grew in lab

Question 24

what enzyme is tested for a starch agar

Answer 24

amylase is the enzyme and it hydrolyzes the starch

Question 25

how to do a starch agar test

Answer 25

1. label starch plate 2. aseptically streak a single line of bacteria 3. invert the plate and place in tub

Question 26

after incubation, what do you add to see if the bacteria grew on the starch agar and what does it look like if it can grow

Answer 26

you add iodine for 10-15 minutes with lid on a halo will be observed if amylase was produced during growth, if amylase was not produced the agar will stay dark

Question 27

**carbohydrate (sugar) fermentation tubes** what is testing for

Answer 27

whether the bacteria ferments that particular sugar

Question 28

**carbohydrate (sugar) fermentation tubes** what do pos and neg results look like (colors and bubble)

Answer 28

pos: yellow neg: red bubble: a gas was produced b/c some gas was trapped as it was produced

Question 29

**carbohydrate (sugar) fermentation tubes** What do the pos and neg results mean?

Answer 29

K: tube remained red; bacteria could NOT ferment that sugar A: tube turned yellow; bacteria COULD ferment that sugar but gas was not produced Ag: tube turned yellow; bacteria COULD ferment that sugar and gas was produced during fermentation

Question 30

**Protocol** MR

Answer 30

1. label tube 2. aseptically inoculate MR tube with bacteria 3. incubate for 36-48 hr at 37 4. add 4 drops of methyl red to each tube

Question 31

**Testing for** MR

Answer 31

detects production of mixed acids from the fermentation of glucose produced by the mixed acid fermentation pathway

Question 32

**Pos and Neg results; what they mean** MR

Answer 32

pos: tube turned red bacteria uses mixed acid fermentation pathway neg: tube remained yellow; no color change bacteria does not use mixed acid fermentation pathway

Question 33

**Protocol** VP

Answer 33

1. label tube 2. aseptically inoculate VP tube with bacteria 3. incubate for 36-48 hr at 37 4.add 14 drops of VP-A and 18 drops of VP-B vortex gently and let sit with lid off for 30 mins

Question 34

**Testing for** VP

Answer 34

The VP test detects the 2, 3 butanediol pathway, where more neutral products are made (only a little acid). An intermediate in the 2, 3 butanediol pathway is acetoin (aka acetyl-methyl-carbinol), which is the specific compound detected by the VP test reagents.

Question 35

**Pos and Neg results; what they mean** VP

Answer 35

pos: tube had red layer bacteria uses 2,3 butanediol pathway neg: tube did not have a red layer bacteria does not use 2,3 butanediol pathway

Question 36

**Protocol** Citrate slant

Answer 36

1. label citrate slant tube 2. aseptically inoculate citrate slant by zig-zagging the bacteria up the surface of the slant 3. incubate tube for 24-48 hr at 37 degrees celcius

Question 37

**Testing for** Citrate slant

Answer 37

if the bacteria use citrate as their only source of carbon and energy

Question 38

**Pos and Neg results; what they mean** Citrate slant

Answer 38

pos: tube turned blue bacteria uses citrate as their only source of carbon and energy neg: tube remained green; no color change bacteria does not use citrate as their only source of carbon and energy

Question 39

**Protocol** TSI

Answer 39

1. label tube 2. aseptically stab the needle into the butt of the tube and streak up the surface of the slant 3. incubate slant for 18-24 hr at 37 degrees celcius

Question 40

**Testing for** TSI

Answer 40

if bacteria ferments (slant) ferments lactose and/or sucrose (butt) ferments glucose

Question 41

**Pos and Neg results; what they mean** TSI K red A yellow

Answer 41

A/A: slant yellow butt yellow K/K: slant red butt red K/A: slant red butt yellow K/H2S+: slant red butt black precipitate A/H2S+: slant yellow butt black precipitate

Question 42

**EMB** what does it inhibit

Answer 42

gram pos

Question 43

**EMB** what it allows to grow

Answer 43

gram neg

Question 44

**EMB** how it differentiates gram neg

Answer 44

ability to ferment lactose (metallic green or dark purple/ dark pink are gram neg lactose fermenters and colorless, creamy, or light pink colonies are gram neg that cannot ferment lactose)

Question 45

**EMB** identify on sight how does e. coli look like

Answer 45

e coli or other bacteria that ferments lactose turns metallic green/ dark purple bacteria that cannot ferment lactose are colorless, creamy, light pink

Question 46

**MSA** what does it inhibit

Answer 46

bacteria that are not halotolerant (cannot tolerate high salt)

Question 47

**MSA** what it allows to grow

Answer 47

halotolerant bacteria like Staphylocossus species

Question 48

**MSA** what it differentiates

Answer 48

halotolerant by mannitol fermentation

Question 49

**MSA** identify on sight differentiate s. aureus and s. epidermis

Answer 49

S. aureus turned agar yellow means there is growth S. epidermis remained red but growth is visible