Microbiology Lab Bio126L Exam 1

Front 1

What is the equation for resolution?

Back 1

Resolution (diameter of the smallest visible object) =

(lambda, wavelength)/
2*(N.A. object, numerical aperature)

Front 2

Define parfocal.

Back 2

A set of lenses whose focal points lie in the same plane

Front 3

What are the 10 microscope problems?

Back 3

Slide is upside down
Lens locked into safety position
Oil on low power lenses
No immersion oil used
Focus on wrong thing
Phase contrast filter in wrong position
Magnification too low
Not enough light
Too much light
Cord in way

Front 4

What function does oil immersion serve?

Back 4

Oil has nearly the same refractory index as the glass slide (allowing more light to come through?)

Front 5

What are the 2 types of culture media?

Back 5

Complex and
Chemically-defined (synthetic)

Front 6

Name some qualities of complex media.

Back 6

Provides excess of all nutrients
Minimize lag, maximize growth
High productivity
Permits many organisms to grow

Front 7

Name some qualities of chemically-defined media.

Back 7

Great value in studying the minimum nutritional requirements of a particular microorganism

Front 8

What is the process by which one handles materials without introducing unwanted microorganisms?

Back 8

Aseptic technique

Front 9

What simple device is used for sterile transfer of microorganisms?

Back 9

Inoculating loop

Front 10

Why is a three-phase streak useful?

Back 10

You can dilute a mixed culture and be able to select one colony/CFU

Front 11

What are the 2 type of oblique light microscopy?

Name the importance of each.

Back 11

Reflected - allows you to see morphology of colonies inoculated on a dark agar

Transmitted - allows you to see the interior structure of colonies

Front 12

What is another name for oblique, transmitted light microscopy?

Back 12

The "Henry technique"

Front 13

What is a mordant?

Back 13

A mordant is a compound that sets a dye, i.e. iodine

Front 14

What are the 4 reagents used in a Gram Stain? (in order)

Describe each reagent's purpose

Back 14

1 - Crystal violet - primary stain

2 - Iodine - mordant (set dye)

3 - Ethanol - decolorizing agent of gram (-) negative cells

4 - Safranin - counterstain for gram (-) negative cells

Front 15

Describe peptidoglycan levels for both Gm+ and Gm- cells.

Back 15

Gm+ have cell walls with THICK peptidoglycan layers

Gm- have cell walls with THIN peptidoglycan layers

Front 16

What color are Gm+ and Gm- cells, respectively, after a gram stain?

Back 16

Gm+ = purple

Gm- = pink

Front 17

What is a "pure culture" of a bacterium?

Back 17

Only one bacterial strain is present

Created from one CFU

Front 18

List the 5 (FIVE) categories that microorganisms can be divided into, based on their oxygen tolerance.

Back 18

Obligate aerobe

Microaerophile

Facultative anaerobe

Aerotolerant anerobe

Obligate anaerobe

Front 19

What are the 4 (FOUR) types of population interactions?

Back 19

Commensalism

Synergism/symbiosis

Anatagonism/parasitism

Neutralism

Front 20

What are siderophores?

Back 20

Siderophores are iron-binding organic acids produced by microorganisms

Front 21

What is a siderophore auxotroph?

Back 21

An organism that cannot synthesize its own siderophore

Front 22

Give an example of a siderophore auxotroph.

Back 22

Microbacterium flavescens

Front 23

What is MIC?

Back 23

Minimal Inhibitory Concentration (antibiotics)

Front 24

What test is done to gauge antibiotic sensitivity?

Back 24

The Kirby-Bauer Test

Antibiotic-impregnated paper discs
Zone of Inhibition (ZOI) = diameter

Front 25

Will Microbacterium flavescens grow on blood slant agar without siderophores present?

Why? OR Why not?

Back 25

Yes. The hemoglobin in blood satifies the iron requirement.

Front 26

What are the commercially created siderophores called?

Back 26

Desferal discs

Front 27

Can you safely assume that organism that do not stimulate growth of Microbacterium flavescens don't make a siderophore?

Back 27

No, M. flavescens could have simply not been able to remove its siderophore.

Front 28

What media is both selective and differential?

How does it accomplish each of these?

Back 28

MacConkey's Agar.

Selective --
prevents growth of gram+ bacteria due to presence of crystal violet and bile salts (CV prevents growth by ___ and bile salts prevent growth by ___)

Differential --
distinguishes lactose fermenting Gram- bacteria because they because pink-red in color and may be surrounded by a zone of precipitated bile

Front 29

What is the equation to calculate the original titer?

Back 29

# colonies/
-------------------------------------------------
(volume plated)*(cumulative dilution)

Front 30

Name the 2 methods of dilution plating.

Describe the location of resulting colonies

Back 30

Dilution POUR plating - colonies in the agar

Dilution SPREAD plating - colonies on surface agar

Front 31

What number of colonies are countable, TFTC, or TMTC?

Back 31

Countable 30-300

TFTC <30

TMTC >300

Front 32

The measurement of the amount of light absorbed when a beam is passed through a colored solution is called ___________.

Back 32

Colorimetry

Front 33

The measurement of light absorption by particles in suspension is called ________.

Back 33

Turbidimetry

Front 34

What 4 (FOUR) compounds were used for the Carbohydrate Fermentation tests?

Back 34

Glucose (monosaccharide)
Lactose (disaccharide)
Sucrose (disaccharide)
Mannitol (alcohol)

Front 35

What is the purpose of the Durham tube?

Back 35

Trap gases that are produced by aerogenic fermenters

Front 36

Bacteria that ferment carbohydrates usually have what relationship with oxygen?

Back 36

Facultative anaerobes

Front 37

What is the purpose of the Carbohydrate fermentation test?

Back 37

Determine what sugars an organism is able to ferment by detecting a net accumulation of acids and gas (AEROGENIC organisms) or only acids (ANAEROGENIC organisms)

Front 38

What compound detects the presence of acidic fermentation?

Back 38

Phenol red

Red --> Orange-red (No reaction)
Orange and yellow (slightly acid)
Yellow (Acid)

Front 39

For the carbohydrate fermentation test, what does the symbol of A mean?

Back 39

Acid no gas (ANAEROGENIC)

Front 40

For the carbohydrate fermentation test, what does the symbol of an A with a circle mean?

Back 40

Acid with gas (AEROGENIC)

Front 41

For the carbohydrate fermentation test, what does the symbol of an A with a dotted-circle mean?

Back 41

Acid with small amount of gas (AEROGENIC)

Front 42

For the carbohydrate fermentation test, what does the symbol of s/A mean?

Back 42

Slightly acidic

Front 43

For the carbohydrate fermentation test, what does the symbol of NR mean?

Back 43

No reaction

Front 44

For the carbohydrate fermentation test, what does the symbol of NR++ mean?

Back 44

Alkaline (degradation of peptone)

Front 45

What intracellular enzyme complex is detected by the Indole Test?

Back 45

Tryptophanase is detected by the Indole test

Tryptophanase degrade typ by splitting off INDOLE

Front 46

What will detect the presence of Indole? How?

Back 46

Kovac's reagent

Indole + p-dimethyl... = Insoluble red compound

Butanol -- extract and concentrate red compound -- float

Front 47

The degradation of H2O2 in most organisms capable of good growth under aerobic conditions (aerobes) is accomplished by which enzyme?

Back 47

Catalase (a heme protein like the cytochromes)

Front 48

How can catalase activity be detected?

Back 48

Effervescence of O2 when H2O2 is added (BUBBLES)

Front 49

What will indicate a positive Motility Test?

Back 49

Red growth away from the stab line

Semisolid, soft agar

2,3,5-triphenol... color-->red (when growing bacteria present)