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Microbiology > Lab Exam 1 > Flashcards

Lab Exam 1 Flashcards

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1
Q

What does “ubiquitous” mean?

A

that they are found everywhere

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2
Q

What can microorganisms be isolated from?

A
  • Soil
  • Water
  • Plants
  • Animals
  • Placed like the hot acid pools in Yellowstone
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3
Q

Are all microorganisms ubiquitous?

A

Not EVERY species is, but it applies to microorganisms as a group

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4
Q

What do you call microorganisms that do not reside on or in a specific plant or animal host and are not known to cause disease?

A

Free-living and nonpathogenic

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5
Q

Saprophytes play an important role in decomposition of the ecosystem. What is a Saprophyte?

A

A plant, fungus, or microorganism that lives on dead or decaying organic matter

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6
Q

What are the three types of relationships between microorganisms and their host?

A

Pathogenic, Mutualism, and Commensalism

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7
Q

Pathogenic relationship

A

Microorganism causes damage to the host

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8
Q

Mutualistic relationship

A

Both the host and the microbe benefit

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9
Q

Commensal relationship

A

Microbe benefits but no effect on host

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10
Q

What are opportunistic pathogens?

A

Pathogens that take advantage of a situation that is not normally available

-They inhabit our bodies and are capable of producing a disease state if introduced into a suitable part of the body

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11
Q

Reservoir

A

Any area where a microbe with potential to cause infection resides

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12
Q

What is the composition of Blood Agar?

A

5% Sheep blood in a Tryptic Soy Agar (TSA) Base

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13
Q

What is the purpose of blood agar?

A

To differentiate bacteria based on their hemolytic characteristics

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14
Q

Three major types of hemolysis

A

Beta, Alpha, and Gamma

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15
Q

Beta hemolysis

A

Complete destruction; results in cleaning of the medium

  • has a yellow halo around the microbes in the TSA plate
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16
Q

Alpha hemolysis

A

Partial destruction; results in greenish discoloration of the medium

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17
Q

Gamma hemolysis

A

No hemolysis

-has neither the beta or alpha characteristics and will likely appear like nothing happened

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18
Q

Germicides

A

Refers to substances or systems, both chemical and physical, that prevent the spread of pathogens

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19
Q

What are the three categories of germicides?

A

Decontamination, Disinfection, and Serilization

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20
Q

Decontamination

A
  • Lowest level of control
  • Defined as “reduction of pathogenic microorganisms to a level at high items are safe to handle without protective attire”
    -involves the removal of all or most organic and inorganic matter
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21
Q

Disinfection

A
  • next level of control
  • kills most of targeted pathogens, but typically do not kill large numbers of spores
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22
Q

What are the two types of disinfectants?

A

Chemical sterilants and antiseptics

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23
Q

Examples of methods of disinfection

A
  • typically liquid or gaseous chemical agents
  • dry heat
  • moist heat
  • UV light
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24
Q

Sterilization

A
  • highest level of pathogen control
  • can kill all viable organisms, even spores
  • achieved by chemicals, gases, incineration, dry heat, moist heat, ethylene oxide gas, ionizing radiation, low-temp plasma, or low-temp ozone
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25
Q

What is the most effective and most common method of sterilization? What is an example of it?

A

Steam Sterilization
Ex: Autoclave

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26
Q

What is the sterilizing temperature for autoclaving and how long should it be done for?

A

Between 121 and 127 degrees C for at least 15 at the optimum temperature

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27
Q

What is the only way to determine with certainty that sterilization has been achieved?

A

Biological indicators

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28
Q

What does aseptic transfer mean?

A

Transfer of living microbes from one place to another without contamination of the culture, the sterile medium, or the surroundings

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29
Q

What is a culture?

A

A medium that contains living microbes

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30
Q

What is a pure culture?

A

A culture that contains a single species

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31
Q

What is a mixed culture?

A

A culture that contains multiple species

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32
Q

What assumption should be made about cultures?

A

All cultures are assumed to be mixed prior to obtaining isolation

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33
Q

Broths

A

Used to grow microbes when fresh cultures or large number of cells are required

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34
Q

Agar Slants

A

Used to grow stock cultures that can be refrigerated after incubation and maintained for several weeks

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35
Q

What is Plated media used for?

A

Typically used for obtaining isolation of species, differential testing, and quantifying bacterial densities

36
Q

methods of isolation

A

Spread plate, streak plate, and pour plate

37
Q

Spread Plate Technique

A

Microbial sample is deposited on an agar plate and spread uniformly. After incubation, a portion of isolated colon can be transferred to a sterile medium to begin a pure culture.

-Can be used to quantify cell density of a broth culture

38
Q

What are growth characteristics influenced by?

A
  • nutrient availability
  • temperature
  • incubation time
39
Q

Basic categories of colony morphology

A

Shape, margin, elevation, texture, color, and optical properties

40
Q

What are agar slants used for?

A

Cultivation, maintenance, and storage of stock cultures

41
Q

growth characteristics for organisms cultured on a slant

A
  • Filiform
    • dense and opaque with a smooth edge
  • Friable
    • Crusty
  • Spreading Edge
    • produced by motile organisms
  • Pigmented or translucent/transparent
42
Q

Growth patterns in broth

A
  • Pellicle
    • growth floats on top of the medium
  • Sediment
    -growth sinks to the bottom
  • Uniform fine turbidity
    -Flocculent
    -clumped growth
43
Q

Who developed the concept of the pure culture in the 1850’s?

A

Louis Pasteur

44
Q

What did Robert Koch develop a procedure for the the 1880’s?

A

Streaking for isolation

45
Q

What is the purpose of streaking for isolation?

A

To obtain isolated colonies that can then be used to obtain a pure culture

46
Q

Bright-field microscopy

A

Produces an image made from light transmitted through a specimen

47
Q

total magnification = magnification of ______ _____ x magnification of ________ _____

A

Ocular lens; objective lens

48
Q

Resolution

A

The clarity of an image

49
Q

Ocular micrometer

A

Composed of uniform but unspecified graduations and must be calibrated before used to measure specimens

50
Q

Stage micrometer

A

A microscope slide containing a ruler with 100 micrometers

51
Q

How many micrometers is 0.01mm?

A

10

52
Q

How are bacterial stains useful?

A

They are used to determine:
- Cell size
- Cell morphology
- cellular arrangement
- other bacterial structures or differentiating features

53
Q

What is an important first step in identifying bacterial species?

A

Determining Cell Morphology

54
Q

Types of cell morphologies:

A
  • spheres
    -cocci
  • rods
    • bacilli
  • spirals
    • spirilla
55
Q

What is pleomorphism?

A

A single species that exhibits a variety of cell shapes- slender, ellipsoidal, or ovoid rods - within a given sample

56
Q

Pairs of cells have the prefix:

A

“Diplo”

57
Q

Chains of cells have the prefix:

A

“Strepto”

58
Q

Tetrads arrangement name example with cocci shape

A

Micrococcus

59
Q

Cube “sarcina” cell arrangement name example with cocci shape

A

Sarcina

60
Q

What is the prefix for an irregular cluster?

A

‘Staphylo”

61
Q

Name example for a palisade and angular cell arrangement and a bacilli shape

A

Corynebacterium

62
Q

what do stains contain?

A

A solvent and the chromogen (colored molecule)

63
Q

What do chromogens consist of?

A

The Chromophore (portion of the chromogen that gives it color) and the Auxochrome ( changed portion of the chromogen)

64
Q

What is the purpose of a negative stain?

A

To determine morphology and cellular arrangement in bacteria that are too delicate to withstand heat-fixing

65
Q

Theory behind a Negative Stain

A
  • uses a dye solution in which the chromogen is acidic
  • acidic chromogen gives up a H+ and becomes negatively changed
  • negative charge on bacterial surface repels the negatively charged chromogen
  • cell remains untainted against a colored background
66
Q

What is a Simple Stain?

A

Smear is stained with a single dye that stains the cells all the same color

-differentiation of cell types or structures is NOT the objective!

67
Q

Differential stains

A

Detect differences between organisms or between parts of the same organism

-used more frequently than simple stains because they provide additional information

68
Q

What is part of the group of stains are sometimes referred to as structural stains?

A
  • Acid-fast stains
  • Gram stain
  • Capsule stain
  • Endospore stain
  • Flagella stain
69
Q

What is the purpose of simple stains?

A

Stain heat-fixed cells with a colored dye to make them more visible under a microscope

70
Q

Simple stain theory

A
  • Auxochrome picks up a H+ or loses an OH- and becomes positively charged
  • Attracted to the negative charges on the surface of most bacterial cells
71
Q

what are examples of simple stains?

A
  • Methylene Blue
    -Crystal Violet
  • Safranin
  • Carbolfuchsin
72
Q

Differential stains are used to differentiate between _________ and _________ cells

A

Gram positive and Gram negative

73
Q

Gram-Positive

A

Bacteria have a very thick cell wall made of peptidoglycan and NO outer membrane

74
Q

Gram-negative (pink)

A

Bacteria have a thin cell wall made of peptidoglycan and have an outer membrane

75
Q

Why do gram positive stains resist coloration?

A

It is because of the thicker peptidoglycan layers and greater cross-linking due to teichoic acids. It traps the crystal violet-iodine complex and resists decoloration

76
Q

What is the most critical and most likely step that is the source of inconsistency? Why?

A

Decolonization because you could cause over-decolorization and under-decolorization

77
Q

What are the three techniques that are executed poorly for variable results?

A
  • Decolorization is done wrong
  • Improper preparation of the emulsion
  • Age of the culture
    • best cultures are no older than 24 hours because they can lose their ability to retain the crystal violet-iodine complex
78
Q

What is an Acid Fast Stain based on?

A

The presence of mycolic acids in the cell wall of acid-fast positive organisms

79
Q

Mycolic acid

A

A waxy substance that provides a higher affinity for the primary stain and resistance to decoloration by an acid alcohol solution

80
Q

what is an important differential stain used to identify bacteria in the genus Mycobacterium?

A

Acid-fast stain

81
Q

Acid-Fast Positive final color is _____ while Acid-Fast Negative final color is _______

A

Pink; green

82
Q

Endospore

A

-Dormant form of the bacterium that allows it to survive poor environmental conditions
-Resistant to heat and chemicals because of tough outer covering made of keratin

83
Q

Spore Location meanings

A
  • Central
    • middle of the cell
  • Terminal
    • end of cell
  • Subterminal
    • between end and middle
84
Q

Endospore Stain

A

Differential stain used to detect presence or absence of spores in bacterial cells

85
Q

which two genera produce spores?

A

bacillus and Clostridium

86
Q

If a spore producer is present, it will have a ______ spore against the red-stained mother cell

A

Malachite Green

87
Q

Categories of flagellation

A

-Monotrichous (single flagellum)
-Peritrichous (flagella all around)
- Amphitrichous (flagella on both ends)
- Lophotrichous (flagella on one end)

Microbiology (11 decks)

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