Microbiology Lab Quiz 1

Front 1

mixed culture

Back 1

culture with more than one type of microorganism

Front 2

Why is agar such a good gelling agent?

Back 2

Majority of microorganisms do not have the enzymes to degrade the agar, and it does not melt unless it is at boiling temperature.

Front 3

What do microorganisms need to grow?

Back 3

nitrogen, energy source (e-), carbon, water

Front 4

defined medium

Back 4

when the exact components and amounts are known

Front 5

complex medium

Back 5

if the medium contains peptones (extracts from yeast, veggies, meat, etc)

Front 6

streak plate

Back 6

method of diluting a bacterial sample on a solid plate

Front 7

selective medium

Back 7

inhibits growth of certain groups of microorganisms (EMB- inhibits gram +)

Front 8

EMB

Back 8

-eosin methylene blue
-inhibits gram +
-can also differentiate between lactose fermenting or non-fermenting gram (-) because it contains sugars (lactose and sucrose), and if organism ferments sugar to acid, then it will absorb dye, turning it black)

Front 9

enriched medium

Back 9

promotes growth of certain organisms (media with something extra like blood or yolk)

Front 10

differential medium

Back 10

differentiates between organisms (by pH, lactate, etc)

Front 11

Mannitol salt agar

Back 11

-contains carbohydrate and pH indicator (yellow if acidic, red if basic). therefore if organism ferments sugar, it will give off a yellow halo
-also high in salt content (7.5%) so organisms that cannot tolerate high salt will not grow

Front 12

MacConkey agar

Back 12

contains lactose and neutral red pH indicator (turns red when acidic)

Front 13

blood agar

Back 13

microorganisms that secrete hemolysin (lyses blood) which will "eat" the blood cells around the colony so you get a clear area around it, or green if it is a hemolysin that partially lyses

Front 14

Time before you must transfer your slant pure culture

Back 14

7-10 days

Front 15

coliforms

Back 15

gram negative lactose fermenting bacili (rod shaped), non-endosporm forming. ex) e. coli

Front 16

facultative

Back 16

"optionally"

Front 17

normal flora

Back 17

mostly gram + bacteria that reside on human skin

Front 18

propionibacterium

Back 18

normal flora found in dairy products too. found deep in skin near sebaceous glands.

Front 19

types of colonies you might get from forehead culture

Back 19

a. large, convex, opaque, white (staph)
b. flat, tan, viscid
c. medium, opaque, convex, smooth, pink/brown (propionibacterium)

Front 20

Yeast are eukaryote or prokaryote?

Back 20

eukaryote

Front 21

S1 (Gould) agar

Back 21

-prevents gram + (contains SLS which disrupts the membrane)
-Trimethoprim- antibiotic for facultative anaerobic gram-

Front 22

pseudonoma

Back 22

-produces pigment around the colony which diffuses into media
-gram-, aerobes

Front 23

bacillus

Back 23

gram +, endospore forming bacteria