Microbiology Test 1

Front 1

OBJECTIVE LENS

Back 1

where the initial magnification occurs

Front 2

OCULAR LENS

Back 2

Where the final magnification occurs

Front 3

TYPES OF LENSES

Back 3

low-power, high-power, oil immersion

Front 4

What is the difference between the resolving power and magnifying power of a lens? "parfocal"

Back 4

as long as you leave the same focus when changing the objectives, it stays in focus.

Front 5

Why is oil necessary when using the 90x to 100x?

Back 5

because the oil in creases the resolution.

Front 6

What is the function of the iris diaphragm and the substage condenser?

Back 6

The diaphragm is to control the amount of light passing into the condenser. The condenser is to control/condense the light going into the diaphragm.

Front 7

What is meant by the limit of resolution?

Back 7

The minimum between two points to still have resolution.

Front 8

What are the three bacterial shapes observed?

Back 8

Cocci (round)
Bacillus (rod)
Spiralus (spiral)

Front 9

What is the most commonly used objective?

Back 9

Oil immersion (100x), because it provides the best magnification with the best resolution.

Front 10

If 5x instead of 10x oculars were used in your microscope with the same objectives, what magnifications would be achieved?

Back 10

5x x 10x= 50x
5x x 40x= 200x
5x x 100x= 500x

Front 11

BACTERIAL SMEAR

Back 11

Dried preparations of bacterial cells on a glass slide.

Front 12

HEAT-FIXING

Back 12

passing the side through a hot portion of the bunsen burner.

Front 13

FIXED

Back 13

bacteria killed and stuck to slide

Front 14

CHROMOGEN

Back 14

simple stain or dye

Front 15

What are two purposes of heat fixation?

Back 15

Kills bacteria and adheres bacteria to slide.

Front 16

What is the purpose of simple staining?

Back 16

To create contrast between bacteria and their environment.

Front 17

Why are basic dyes more successful than acidic dyes?

Back 17

The positively charged basic solutions bind to the negatively charged molecules of bacteria.

Front 18

Name the three basic dyes

Back 18

Crystal Violet
Methylene Blue
Carbol Fusion

Front 19

MEDIA

Back 19

The nutrient preparations are used for culturing microorganisms

Front 20

MEDIA TYPES

Back 20

Chemically defined
Complex media

Front 21

CHEMICALLY DEFINED

Back 21

when we know exactly whats in the media and the exact amounts

Front 22

COMPLEX MEDIA

Back 22

An abundance of nutrients, vitamins, etc; that are needed for growth.

Front 23

TSA

Back 23

Type of complex media, Tryptic Soy Agar (solidifying agent)

Front 24

TSB

Back 24

Type of complex media, Tryptic Soy Broth

Front 25

MEDIA FORMS

Back 25

Liquid: broth
Solid: agar mixed in with media
Semi-solid: lower percentage of agar

Front 26

AUTOCLAVING

Back 26

-121 degrees celsius to sterilize
-15 lb per square inch of pressure, don't physically boil because of pressure, for 15 mins.

Front 27

DRY-HEAT

Back 27

Putting in a oven for 160-170 degrees celsius, for at least 2 hours

Front 28

BACTERIOLOGICAL FILTER

Back 28

-22 micrometers of filter out into bottom
-for when some media can't withhold heat

Front 29

UV

Back 29

-260 nm, does not penetrate substances very effectively
-only used for few situations

Front 30

ETHYLENE GAS

Back 30

-used for heat sensitive items
-effective because penetrates packing materials.

Front 31

What are 3 mains microbiological culture media types?

Back 31

-Solid
-Liquid
-Semi solid

Front 32

Defined medium vs complex medium.

Back 32

Defined: pure chemicals of known amount
Complex: media of unknown amounts.

Front 33

Why are culture media sterilized before use?

Back 33

To ensure there is no consisting life in them

Front 34

Describe three ways for sterilizing culture media:

Back 34

-Autoclaving
-Dry-heat
-Bacteriological filter

Front 35

INOCULATING NEEDLES AND LOOP

Back 35

Used to transfer organisms to one culture to another

Front 36

PURE CULTURE

Back 36

Single organism, one thing in a tube or on a slide

Front 37

SUBCULTURE

Back 37

Something is transferred to a new media for further growth

Front 38

ASEPTIC TECHNIQUE

Back 38

When handeling a microorganism, the technique are designed to prevent contamination.

Front 39

What is the purpose of flaming in aseptic technique?

Back 39

Sterilization; to kill contaminants

Front 40

What is the purpose of subculturing?

Back 40

To transfer a growth of bacteria to a new media to create a new pure culture

Front 41

How would you determine whether culture media is sterile before you use is?

Back 41

Nothing should be growing on it or in it and it should be sealed.

Front 42

What are some signs of growth in a liquid medium?

Back 42

even, layered, sedimented, clusters, and cloudiness.

Front 43

DIFFERENTIAL STAINING

Back 43

bacteria differ from one another chemically and physically and may react differently to a given stain procedure.

Front 44

GRAM STAIN

Back 44

Invented by christian gram, two different types.

Front 45

GRAM POSITIVE

Back 45

Bacteria retain the color of the primary dye (Crystal Violet)

Front 46

GRAM NEGATIVE

Back 46

Bacteria loose the primary dye (Crystal Violet) when washed in a decolorizing solution (Ethanol) and than take on the color of the new solution (Safranin)

Front 47

What is the difference between a simple stain and a differential stain?

Back 47

Simple: all 1 color and no ethanol
Differential: multi-step and multi-colorizations

Front 48

Name the reagents used in a gram stain

Back 48

Mordant, primary stain, de-colorizer, counter-stain

Front 49

MORDANT

Back 49

Iodine- tightly binds the dye to the cells

Front 50

PRIMARY STAIN

Back 50

Crystal Violet- stains all the cells purple

Front 51

DE-COLORIZER

Back 51

95% Ethanol- removes color from the gram negative cells

Front 52

COUNTER-STAIN

Back 52

Safranin- stains the gram negative cells pink.

Front 53

Which step is the most crucial or most likely to cause poor results in gram stain?

Back 53

The 95% Ethanol step, because if it is added for too long it will remove too much color.

Front 54

Why must young cultures be used when doing a gram stain?

Back 54

Gram positive cultures may turn gram negative if they get too old.

Front 55

What is meant by gram variable?

Back 55

Some cells in the same culture will be gram positive and some will be gram negative.

Front 56

PURE CULTURE

Back 56

In order to adequately study and characterize an individual bacteria species, you need a pure culture.

Front 57

SPREAD PLATE

Back 57

A small volume of dilute bacteria mixture containing 100 to 300 cells or less is transferred to the center of agar and spread.

Front 58

COLONY

Back 58

After incubation, some dispersed cells develop into isolated colonies; viable with the naked eye.

Front 59

What is a bacterial colony?

Back 59

-A large growth visible with the naked eye.
-Comes from one cell, pure colony.

Front 60

What is the purpose of Ethanol in the Spread-Plate technique?

Back 60

Coats the glass rod, which is lit on fire, kills the contaminants

Front 61

Why is it necessary to use only diluted cultures that contain 100 to 300 cells for a successful spread plate?

Back 61

So you don't have too many colonies forming and can't visibly make distinctions between two separate colonies.

Front 62

What is the purpose of the spread-plate technique?

Back 62

To create dilute solutions of bacteria spread over an area so that separate colonies can form.

Front 63

In all routine laboratory work, petri plates are labeled on the bottom, why?

Back 63

Because they are placed in the incubador upside down so that the condensation doesn't build up and drip.

Front 64

STREAK-PLATE

Back 64

Isolated, pure colonies, the bacterial mixture is transferred to the edge of an agar plate with an inoculating loop and then streaked out over the surface in one of the several patterns.

Front 65

SELECTIVE MEDIA

Back 65

Favors the growth of particular media

Front 66

DIFFERENTIAL MEDIA

Back 66

Distinguishing between different groups of bacteria and even permit tentative identification of microorganisms based on their biological characteristics.

Front 67

MANNITOL SALT AGAR

Back 67

Type of differential media, used to isolate staphylococci

Front 68

EOSIN METHYLENE BLUE AGENT

Back 68

Type of differential media, used to detect E.Coli

Front 69

In the streak-plate, how are microorganisms diluted and spread out to form individual colonies?

Back 69

Cells are deposited into the agar along the way; less and less

Front 70

Which area of a streak-plate will contain the greatest amount of growth? Least amount of growth?

Back 70

-Greatest: box 1, most bacteria
-Least: box 4, least bacteria, most dilute

Front 71

Does each discrete colony represent growth of one cell?

Back 71

Yes, colonies form one cell form one cell, all cells in a colony are identical.

Front 72

How can a streak-plate become contaminated?

Back 72

Not sterilized, etc.

Front 73

ENDOSPORES

Back 73

Structure that develops within the bacterial cells of the gram positive, do not stain easily but once stained they strongly resist de-colorization.

Front 74

SCHAEFFER-FULTON

Back 74

Staining endospores with Malachite Green and heat is used to provide penetration, the rest of the cell is de-colorized and counterstained red.

Front 75

Why is heat necessary to stain endospores?

Back 75

Because it provides stain penetration

Front 76

In the Shaeffer-Fulton endospore what are the primary and counter stain?

Back 76

Primary: Malachite green
Counter: Light red with Safranin

Front 77

Name two disease-causing bacteria that produce endospores?

Back 77

Bacillus Megaterium: a crystalized cell in soil
Bacillus Macerans: elongated cell in soil

Front 78

What is the function of an endospore?

Back 78

Resistance structure capable of surviving long periods in a unfavorable environment and then giving rise to new bacterial cell.

Front 79

STANDARD PLATE COUNT METHOD

Back 79

-an indirect measurement of cell density and reveals info related only to live bacteria.
-Consists of diluting a sample with Saline or Phosphate buffer dilute until bacteria are dilute enough to count accurately.

Front 80

COLONY FORMING UNITS (CFU)

Back 80

The assumption that each viable bacterial cell is separate from all the others and will develop into a single discrete colony.

Front 81

What is a CFU?

Back 81

A colony forming unit is assumed that each single bacterial cell will develop into a single discrete colony.

Front 82

MICROBICIDAL

Back 82

To kill

Front 83

MICROBIOSTATIC

Back 83

To inhibit efficiency of a chemical is often determined with its respect to its ability to determine microbiological

Front 84

PHENOL COEFFICIENT

Back 84

One of the first discovered disinfectants, very effective, but not used today because of its toxicity.

Front 85

List criteria of good disinfectant

Back 85

-Fast acting
-Easy to prepare
-Effective over a wide range of organisms
-Stable, low odor

Front 86

What is the difference between microbicidal and microbiostatic?

Back 86

-Microbicidal is killing organisms
-Microbiostatic is inhibiting growth of microbes

Front 87

What physical factors can influence the activity of a disinfectant?

Back 87

-# of bacteria
-Temperature (warm is better)
-pH (acidic is better)
-Log phase
-Gram positive easier to kill

Front 88

Why do microorganisms differ in their response to disinfectants?

Back 88

Different organisms have different cell wall structures, so some disinfectants can penetrate certain organisms easier than others.

Front 89

KIRBY-BAUER

Back 89

The sensitivity disk method used to determine antibiotic susceptibility.
-Take antibiotics and impregnates onto paper disks and than placed on a seeded Mueller-Hinton agar plate using a mechanical dispenser or sterile forceps, then incubated for 16-18 hours.

Front 90

ZONE OF INHIBITION

Back 90

Around the disk, is it is measured to the nearest millimeter.
-size depends on sensitivity of specific bacterium to specific antibiotics
-this zone indicates the susceptibility or resistance of bacteria to an antibiotic
-The smaller the more resistant

Front 91

How can you determine the zone of inhibition?

Back 91

-Take a sterile look or swab and streak it through the area of the clearing zone
-transfer those organisms from the loop into new sterile broth or plate and incubate.
-if growth, not killed, then just inhibited.
-if not growth, was killed.

Front 92

What factors must be controlled in the Kirby-Bauer method?

Back 92

Size of the inoculum, distribution of the inoculum, incubation period, depth of the agar, diffusion rate of the antibiotic, concentration of antibiotic in the disk, and the growth rate of the bacterium.

Front 93

Which growth phase is a bacterium most sensitive to an antibiotic?

Back 93

The log phase, when the cells are rapidly growing
-if you add an antibiotic or disinfectant organisms will be interrupted and growth will be halted.

Front 94

What is the difference between an antibiotic and an antimicrobic?

Back 94

-Antibiotic is produced by a microorganism and can inhibit or kill another microorganism.
-Antimicrobic is any substance that inhibits or kills another microorganism.

Front 95

Reasons for bacteria becoming more resistant?

Back 95

-Prescriptions being misused or wrongly given.
-The misuse of antibacterial soaps
-the feeding of animals antibiotics for economic purposes