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BIO150 > Chapter 6 > Flashcards

Chapter 6 Flashcards

1
Q

Facultative Anaerobes

A

growth with oxygen or with no oxygen

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2
Q

Plate counts

A
  • Count colonies on plates that have 30-300 colonies (CFUs)
  • To ensure the right number of colonies, the original inoculum must be diluted via serial dilution
  • Counts are performed on baceria mixed into a dish with agar (pour plate method) or spread on the surface (spread plate method)
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3
Q

Physical Requirements for Growth

A
  • Temperature
  • pH
  • Osomotic Pressure
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4
Q

Direct measurements count microbial _____.

A

cells

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5
Q

Bacterial Division

A

Increase the number of cells, not cell size. (Binary Fission)

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6
Q

Optimum growth temperature for Thermophiles

A

50-60 degrees C

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7
Q

Carbon

A
  • structural backbone of organic molecules
  • Chemoheterotrophs use organic molecules as energy
  • Autotrophs use CO2 (think of photoautotrophs)
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8
Q

Microaerophiles

A

require oxygen concentration lower than air

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9
Q

A pure culture contains…

A

Only one species or strain

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10
Q

Dry weight

A

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

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11
Q

Streak plate method

A

used to isolate pure cultures

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12
Q

Colony

A

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

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13
Q

CFU

A

A colony is often called a colony-forming unit (CFU)

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14
Q

Reducing media

A
  • Used for the cultivation of anaerobic bacteria
  • Contain chemicals (sodium thioglycate) that combine O2 to deplete it
  • Heated to drive off O2
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15
Q

Aerotolerant anaerobes

A

tolerate but cannot use oxygen

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16
Q

Log phase

A

Logarithmic or exponential increase in population

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17
Q

Differential Media

A
  • Allow distinguishing of colonies of different microbes on the same plate
  • Some media have both selective and differential characteristics
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18
Q

Agar

A
  • Complex polysaccharide
  • Used as a solidifying agent for culture media in Petri plates, slants, and deeps
  • Generally not metabolized by microbes
  • Liquefies at 100 degrees Celsius
  • Solidifies at ~40 degrees Celsius
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19
Q

Minimum growth temperature

A
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20
Q

BSL-3

A

Biosafety cabinets to prevent airborne transmission

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21
Q

BSL-2

A

Lab coat, gloves, eye protection

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22
Q

Optimum growth temperature for Hyperthermophiles

A

Optimum growth temperature >80 degrees C

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23
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
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24
Q

Biofilms

A
  • Microbial communities
  • Form slime or hydrogels that dhere to surfaces
    • Bacteria communicate cell-to-cell via quorum sensing
  • Share nutrients
  • Shell bacteria from harmful environmental factors
  • Found in digestive system and sewage treatment systems (can clog pipes)
  • 10000x resistant to microbicides
  • Involved in 70% of infections
    • Catheters, heart valves, contact lenses, dentail caries
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25
Q

Biosafety levels

A

Requirements for handling certain cultures

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26
Q

Phosphorous

A
  • Used in DNA, RNA, and ATP
  • Found in membranes
  • PO4^3- is a source of phosphorus
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27
Q

Lag phase

A

Intense activity preparing for population growth but no increase in population yet

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28
Q

Obligate anaerobes

A

unable to use oxygen and are harmed by it

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29
Q

Organic Growth Factors

A
  • Organic compounds obtained from the environment
  • Vitamins, amino acids, purines, and pyrimidines
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30
Q

Selective Media

A
  • Suppress unwanted microbes and encourage desired microbes
  • Contain inhibitors to suppress growth
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31
Q

Stationary phase

A

Period of equilibrium, microbial deaths balance production of new cells

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32
Q

BSL-4

A
  • Sealed, negatibbe pressure; “hot zone”
    • Exhaust air is filtered twice through HEPA filters
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33
Q

Maximum growth temperature

A
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34
Q

Mesophiles

A

Moderate-temperature-loving

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35
Q

What are the phases of growth?

A
  1. Lag phase
  2. Log phase
  3. Stationary phase
  4. Death phase
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36
Q

Thermophiles

A

Heat-loving organisms

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37
Q

Trace Elements

A
  • Inorganic elements required in small amounts
  • Usually as enzyme cofactors
  • Include iron, copper, molybdenum, and zinc
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38
Q

Hypertonic environments (higher in solutes than inside the cell) cause ________ due to high osmotic pressure

A

plasmolysis

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39
Q

Methods of direct measurement

A
  1. Plate count
  2. Filtration
  3. Direct microscopic count
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40
Q

Optimum growth temperature

A
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41
Q

Culture medium

A

nutrients prepared for microbial growth

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42
Q

BSL-1

A

No special precautions; basic teaching labs

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43
Q

How much time is required for a cell to divide?

A

20 minutes to 24 hours

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44
Q

Direct Microscopic Count

A
  • Volume of a bacterial suspension placed on a slide
  • Average number of bacteria per viewing field is calculated
  • Uses a special Petroff-Hausser cell counter

of bacteria/ml = (# cells counted)/(volume area counted)

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45
Q

Metabolic activity

A

Amount of metabolic product is proportional to the number of bacteria

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46
Q

Inoculum

A

introduction of microbes into a medium

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47
Q

Sterile

A

no living microbes

48
Q

Culture

A

Microbes growing in or on a culture medium

49
Q

Psychrophiles

A

Cold-loving organisms

50
Q

Enrichment Cultures

A

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

Usually a liquid

51
Q

Nitrogen

A
  • Component of proteins, DNA, and ATP
  • Most bacteria decompose protein material for the nitrogen source
  • A few bacteria use N2 in nitrogen fixation
52
Q

Binary fission ______ the number of cells each generation

A

doubles

53
Q

Facultative halophiles tolerate ______ osmostic pressure

A

high

54
Q

Obligate aerobes

A

require oxygen

55
Q

Growth curves are represented _________

A

Logarithmically

56
Q
A
57
Q

Death phase

A

Population is decreasing at logarithmic rate

58
Q

Complex media

A

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

Examples: nutrient broth, nutrient agar

59
Q

Total number of cells =

A

2^number of generations

60
Q

pH needs for growth

  • bacteria
  • molds and yeasts
A
  • Most bacteria grow between 6.5-7.5 pH
  • Molds and yeasts grow between 5-6 pH
61
Q

Acidophiles

A

grow in acidic environments

62
Q

Chemically defined media

A
  • Exact chemical composition is known
    • Fastidious organisms are those that require many growth factors provided in chemically defined media
63
Q

Chemical Requirements

A
  • Carbon
  • Nitrogen, sulfur, and phosphorous
  • Trace elements
  • Oxygen
  • Organic growth factors
64
Q

Extreme or obligate halophiles require _____ osmotic pressure

A

high

65
Q

Sulfur

A
  • Used in amino acids, thiamine, and biotin
  • Most bacteria decompose protein for the sulfur source
  • Some bacteria use SO4^2- or H2S
66
Q

Turbidity

A

Measurement of cloudiness with a spectrophotometer

67
Q

What are the physical requirements of growth?

A
  • Temperature
  • pH
  • Osmotic pressure
68
Q

What are the chemical requirements for growth?

A
  • Carbon
  • Nitrogen, Sulfur, Phosphorous
  • Organic growth factors
  • Oygen
  • Trace elements
69
Q

Microorganisms are classified into what four temperature related categories? What is the preference of each?

A
  • Psychophiles
    • Cold-loving; grows best around 15ºC, but not above 20ºC
  • Psychrotroph
    • Cold-loving; can grow in temperatures from 0ºC to 30ºC
  • Mesophiles
    • moderate temperature loving; can grow between 10º-50º C
  • Thermophiles
    • high temperature loving; can grow between 50º-60º C
  • Hyperthermophiles
    • Survive in very high temperatures; >80ºC
70
Q

What is the best pH for bacterial growth?

A

A neutral range between 6.5-7.5 pH

71
Q

Organisms that can tolerate low pH are called _______.

A

acidophiles

72
Q

When bacteria grow in the medium they produce ______ which can interfere with their own growth. _______ are added in the medium to neutralize the ______.

A

acid

Buffers

acidity

73
Q

_____, _____, and _____ act as buffers.

A

Phosphate salts

Peptones

Amino acids

74
Q

_____ osmotic pressure or a _______ environment can cause ______ in bacteria.

A

High

hypertonic

plasmolysis

75
Q

Plasmolysis

A

loss of water from a cell in a hypertonic solution

76
Q

Mold and yeasts can grow at pH ____.

A

5-6

77
Q

Some organisms can grow well in high concentration of salt are called _________.

A

halophiles

78
Q

Hypertonic environments or high osmotic pressure is used to _____ ______ such as salted fish, james and pickles.

A

preserve food

79
Q

Carbon is required for ______ of _______ in cell.

A

synthesis

structures

80
Q

Chemoautotrophs and photoautotrophs use ______ ______ for making sugars.

A

carbon dioxide

81
Q

Protein synthesis needs ______ and _____.

A

nitrogen

sulfur

82
Q

Chemoheterotrophs use ______ _____ to obtain sugars.

A

organic materials

83
Q

DNA and RNA need _____ and ______.

A

nitrogen

phosphorous

84
Q

Phosphorous is present in the ATP and the phospholipids of the ____ ______.

A

cell membrane

85
Q

Trace elements like iron, copper, molybdenum and zinc are required in minute amount of _______ for _______.

A

cofactor

enzymes

86
Q

What are the 4 differences between aerobes and anaerobes?

A

(not final–need to update)

  1. Anaerobes
    1. Do not use oxygen
    2. Makes lactic acid
    3. Makes ethanol
  2. Aerobes
    1. Uses oxygen
    2. Uses citric acid cycle
    3. Uses oxidative phosphorylation
87
Q

What are biofilms?

A
  • Microbial communities
  • Form slime or hydrogels that adhere to surfaces
    • Bacteria communicate cell-to-cell via quorum sensing
  • Share nutrients
  • Shelter bacteria from harmful environmental factors
  • Found in digestive system and sewage treatment systems; can clog pipes
  • 1000x resistance to microbicides
  • Involved in 70% of infections
    • Catheters, heart valves, contact lenses, dental caries
88
Q

Inside biofilms, cell to cell communication is called _____ _____ which allows them to coordinate their activities.

A

quorum sensing

89
Q

What are the benefits of growing inside the biofilm to the bacteria?

A

The biofilm could protect the microbes from environmental factors; these are not good for humans as they resist antiseptics

90
Q

What is a culture medium and what is inoculum?

A

Culture medium: nutrients prepared for microbial growth

Inoculum: introduction of microbes into a medium

91
Q

Why agar is used for preparing growth medium?

A

Agars have complex polysaccharides which provide nutrients, and are used as a solidifying agent for culture media in petri lates/slants/deeps.

Generally not metabolised by microbes.

(liquifies at 100º C and solidifies at 40º C)

92
Q

Define chemically defined medium and complex medium.

A

Chemically defined medium: exact chemical composition is known

Complex medium: Extracts and digests yeasts, meats, or plants; chemical composition varies batch to batch (examples include nutrient broth and nutrient agar)

93
Q

For the growth of anaerobic organism special media containing _____ ____ (e.g. sodium thioglycolate) is used. The reducing agent reacts with the pxygen and removes it.

A

reducing agent

94
Q

BSL 1 precautions

A

Basic lab safety protocol, basic teaching labs

95
Q

BSL 2 precautions

A

Lab coat, gloves, goggles

96
Q

BSL 3 precautions

A

biosafety cabinets to prevent airborne transmission

97
Q

BSL 4 precautions

A

sealed, negative pressure, “hot zone”

(exhaust air is filtered twice through HEPA filters)

98
Q

How do you preserve bacteria culture? 2 ways

A

Deep-freezing (-50ºC - -95ºC)

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

99
Q

Selective media

A

Suppress unwanted microbes and encourage desired microbes

Contain inhibitors to suppress growth

100
Q

Which method is most common for bacterial growth?

A

Binary fission

101
Q

Differential Media

A

Allow distinguishing colonies of different microbes on the same plate

102
Q

Enrichment culture

A

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

Usually a liquid

103
Q

The time required for the bacteria to divide is called a _________ ______.

A

generation time.

[Think of her example of logarithmic growth from generation 1 (1 cell) to generation 21 (~2 million)]

2number of generations

104
Q

What are the four phases of growth?

A

Lag phase

Log phase

Stationary phase

Death phase

105
Q

Lag phase

A

Different proteins and enzymes are being made during this time to prepare for the division/Log phase. The bacterial cells are adjusting to the environment around them.

106
Q

Draw a diagram of microbial growth phases and describe each phase

A
107
Q

What is the advantage of plate count?

A

It measures the number of viable cells. Each live bacterium makes a colony called Colony forming unit or CFU

< 30 we do not count

> 300 we do not count

You get aerobic mcirobes

108
Q

What is serial dilution? Can you provide an example?

A

When the original inoculum is diluted to ensure the correct number of CFUs.

109
Q

What are the direct methods of counting the microbial cells?

A
  1. Filtration
  2. Plate count
  3. Direct microscopic count
110
Q

Filtration

A

Solution passed through afilter that collects bacteria

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

111
Q

Direct Microscopic Count

A

Volume of bacterial suspension placed on a slide

Average numbber of bacteria per viewing field is calculated

Uses a special Petroff-Hausser cell counter

Niumber of bacter/ml:

Number of cells counted

divided by

Volume of area counted

112
Q

What are two disadvantages to using direct microscopic count?

A

Might count dead cells

Microbes which are motile might be counted twice

113
Q

What is used for indirect method of counting?

A

Turbidity: measurement of cloudiness with a spectrophotometer

Metabolic activity: amount of metabolic product is proportional to the number of bacteria

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

114
Q

Turbidity

A

Measurement of cloudiness with a spectrophotometer

115
Q

Indirect method of counting microbes: metabolic activity

A

Amount of metabolic oroduct is proportional to the number of bacteria

116
Q

Dry Weight

A

Bacteria are filtered, dried, and weighted; used for filamentous organisms

BIO150 (15 decks)

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