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Microbiology > Chp 6 > Flashcards

Chp 6 Flashcards

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Biology 101 flashcards
1
Q

The Requirements for Growth for microbials

A

1) Physical requirements
- Temperature
- pH
- Osmotic pressure

2) Chemical requirements
- Carbon
- Nitrogen, sulfur, and phosphorous
- Trace elements
- Oxygen
- Organic growth factors

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2
Q

Physical requirements for microbial growth… Temp

A

1) Minimum growth temperature
2) Optimum growth temperature
3) Maximum growth temperature

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3
Q

Physical requirements for microbial growth… Temp

1) cold loving
2) moderate temp loving
3) heat loving

A

1) Psychrophiles—cold-loving
2) Mesophiles—moderate-temperature-loving
3) Thermophiles—heat-loving

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4
Q

Psychrotrophs

Grow between what temps

A

0C and 20 to 30C

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5
Q

Psychrotrophs cause

A

Cause food spoilage

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6
Q

Thermophiles

Optimum growth temperature of

A

50 to 60C

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7
Q

Thermophiles are found

A

Found in hot springs and organic compost

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8
Q

Hyperthermophiles Optimum growth temperature

A

> 80*C

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9
Q

Most bacteria grow between pH

A

6.5-7.5

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10
Q

Molds and yeasts grow between pH

A

5-6

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11
Q

Acidophiles grow in what environments

A

acidic

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12
Q

Facultative halophiles tolerate

A

tolerate high osmotic pressure

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13
Q

Hypertonic environments (higher in solutes than inside the cell) cause

A

plasmolysis due to high osmotic pressure

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14
Q

Extreme or obligate halophiles require

A

high osmotic pressure (high salt)

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15
Q

Carbon

A
  • Structural backbone of organic molecules
  • Chemoheterotrophs use organic molecules as energy
  • Autotrophs use CO2
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16
Q

Nitrogen is a component of

A

proteins, DNA, and ATP

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17
Q

A few bacteria use N2 in

A

nitrogen fixation

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18
Q

Most bacteria decompose protein material for the

A

nitrogen source

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19
Q

Sulfur

A
  • Used in amino acids, thiamine, and biotin
  • Most bacteria decompose protein for the sulfur source
  • Some bacteria use SO42– or H2S
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20
Q

Phosphorus

used in

A

DNA, RNA, and ATP

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21
Q

Phosphorus found in

A

membranes

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22
Q

PO43– is a source of

A

phosphorus

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23
Q

Most bacteria decompose protein for the

A

sulfur source

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24
Q

Trace Elements

A
  • Inorganic elements required in small amounts
  • Usually as enzyme cofactors
  • Include iron, copper, molybdenum, and zinc
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25
Q

Obligate aerobes and oxygen

A

requires oxygen

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26
Q

Facultative anaerobic and oxygen

A

grow via fermentation or anaerobic respiration when oxygen is not available

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27
Q

Obligate anaerobes and oxygen

A

oxygen and are harmed by it

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28
Q

Aerotolerant anaerobes and oxygen

A

tolerate but cannot use oxygen

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29
Q

Microaerophiles and oxygen

A

require oxygen concentration lower than air

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30
Q

Singlet oxygen:

A

(1O2−) boosted to a higher-energy state and is reactive

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31
Q

Organic compounds

A
  • obtained from the environment

- Vitamins, amino acids, purines, and pyrimidines

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32
Q

biofilms

A

1) Microbial communities
2) Form slime or hydrogels that adhere to surfaces
3) Bacteria communicate cell-to-cell via quorum sensing
4) Share nutrients
5) Shelter bacteria from harmful environmental factors

33
Q

Biofilms Found in

A

digestive system and sewage treatment systems; can clog pipes

34
Q

Biofilms 1000x resistant to

A

microbicides

35
Q

Biofilms are involved in what percentage of infections

A

70%

Catheters, heart valves, contact lenses, dental caries

36
Q

Culture medium

A

nutrients prepared for microbial growth

37
Q

sterile means

A

no living microbes

38
Q

Inoculum:

A

introduction of microbes into a medium

39
Q

Culture

A

microbes growing in or on a culture medium

40
Q

Culture medium Agar is a

A

1) Complex polysaccharide

2) Liquefies at 100C
Solidifies at ~40C

41
Q

Used as a solidifying agent for culture media in Petri plates, slants, and deeps

A

Agar

42
Q

Agar is Generally not metabolized by

A

microbes

43
Q

Chemically defined media:

A

exact chemical composition is known

44
Q

Fastidious organisms are those

A

that require many growth factors provided in chemically defined media

45
Q

Complex media:

A

extracts and digests of yeasts, meat, or plants; chemical composition varies batch to batch

46
Q

Nutrient broth and Nutrient agar are both examples of

A

complex media: extracts and digests of yeasts, meat, or plants; chemical composition varies batch to batch

47
Q

Reducing media is used for

A

the cultivation of anaerobic bacteria

48
Q

Reducing media contains

A

Contain chemicals (sodium thioglycolate) that combine O2 to deplete it

49
Q

Reducing media is heated to

A

drive off O2

50
Q

Capnophiles

A

-Microbes that require high
CO2 conditions

  • CO2 packet
  • Candle jar
51
Q

Biosafety levels

A
  • BSL-1: no special precautions; basic teaching labs
  • BSL-2: lab coat, gloves, eye protection
  • BSL-3: biosafety cabinets to prevent airborne transmission
  • BSL-4: sealed, negative pressure; “hot zone”
  • Exhaust air is filtered twice through HEPA filters
52
Q

Selective media

A
  • Suppress unwanted microbes and encourage desired microbes

- Contain inhibitors to suppress growth

53
Q

Differential media allow

A

Allow distinguishing of colonies of different microbes on the same plate

54
Q

Some media have both

A

selective and differential characteristics

55
Q

Enrichment Culture encourages

A

the growth of a desired microbe by increasing very small numbers of a desired organism to detectable levels

56
Q

enrichment culture is usually a solid or liquid?

A

liquid

57
Q

A pure culture contains

A

only one species or strain

58
Q

A colony is a

A

population of cells arising from a single cell or spore or from a group of attached cells

59
Q

A colony is often called a

A

colony-forming unit (CFU)

60
Q

The streak plate method is used to

A

isolate pure cultures

61
Q

Preserving Bacterial Cultures

A

Deep-freezing: –50 to –95C

Lyophilization (freeze-drying): frozen (–54 to –72C) and dehydrated in a vacuum

62
Q

Bacterial Division

A

1) Increase in number of cells, not cell size

2) Binary fission
3) Budding
4) Conidiospores (actinomycetes)
5) Fragmentation of filaments

63
Q

Generation Time

A

is time required for a cell to divide

20 mins- 24 hrs

64
Q

Binary fission

A

doubles the number of cells each generation

65
Q

In generation time

Total number of cells =

A

2 number of generations

66
Q

In generation time Growth curves are represented

A

logarithmically

67
Q

Phases of Bacterial Growth

A

1) Lag phase
2) Log phase
3) Stationary phase
4) Death phase

68
Q

Direct measurements–count microbial cells

A

1) Plate count
2) Filtration
3) Most probable number (MPN) method
4) Direct microscopic count

69
Q

Plate Counts, count

A

colonies on plates that have 30 to 300 colonies (CFUs)

70
Q

To ensure the right number of colonies during plate counts, the original inoculum must be diluted via

A

serial dilution

71
Q

Counts are performed on bacteria mixed into a

A

with agar (pour plate method) or spread on the surface of a plate (spread plate method)

72
Q

Filtration

A
  • Solution passed through a filter that collects bacteria

- Filter is transferred to a Petri dish and grows as colonies on the surface

73
Q

The Most Probable Number (MPN) Method

A
  • Multiple tube test
  • Count positive tubes
  • Compare with a statistical table
74
Q

Direct Microscopic Count

A

1) Volume of a bacterial suspension placed on a slide
2) Average number of bacteria per viewing field is calculated
3) Uses a special Petroff-Hausser cell counter

75
Q

Direct Microscopic Counts equation

A

Number of bacteria/ml= number of cells divided by volume of area counted

76
Q

Turbidity

A

measurement of cloudiness with a spectrophotometer

77
Q

Metabolic activity

A

amount of metabolic product is proportional to the number of bacteria

78
Q

Dry weight

A

bacteria are filtered, dried, and weighed; used for filamentous organisms

79
Q

estimating bacterial numbers by indirect methods

A

Turbidity

Metabolic Activity

Dry Weight

Microbiology (9 decks)

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