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Microbiology- HLSC 124 🦠 > Microbio Chapter 6- Microbial Growth > Flashcards

Microbio Chapter 6- Microbial Growth Flashcards

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1
Q

What factors determine growth of prokaryotes?

A

Temperature
pH
Osmotic pressure
Oxygen

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2
Q

Which of the growth factors are physical factors?

A

Temperature
pH
Osmotic pressure

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3
Q

Which of the growth factors is a chemical factor?

A

Oxygen

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4
Q

What are the three primary groups made on the basis of their preferred temperature?

A
  1. Psychrophiles
  2. Mesophiles
  3. Thermophiles
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5
Q

What general temperature do psychrophiles prefer?

A

Cold temps

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6
Q

What general temperature do mesophiles prefer?

A

Moderate temps

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7
Q

What general temperature do thermophiles prefer?

A

Hot temps

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8
Q

What are the two divisions of psychrophiles?

A

True
Pyschotrophs

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9
Q

What temperature can True psychrophiles start to grow?

A

0 degrees celsius

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10
Q

What is true psychrophiles optimum temperature?

A

15 degrees celsius

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11
Q

What temperature can true psychrophiles not grow at?

A

20-25 degrees celsius

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12
Q

Do true psychrophiles cause disease?

A

No they are non-pathogenic

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13
Q

What is the other name for pyschrotrophs?

A

Falcutative

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14
Q

What temperature can pyschrotrophs start to grow?

A

0 degrees celsius

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15
Q

What is pychrotrophs optimum temperature?

A

20-30 degrees celsius

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16
Q

What temperature can pyschrotrophs not grow at?

A

30 degrees celsius

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17
Q

What do Psychrotrophs often cause?

A

Food spoilage even when refrigerated its just slowly degrades food
-mold, odour,slime

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18
Q

What temperatures can Mesophiles start to grow?

A

25-40 degrees celsius

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19
Q

What is Mesophile sotimum temperature?

A

37 degrees celsius

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20
Q

What temperature can Mesophiles not grow?

A

50 degrees celsius

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21
Q

Are Mesophiles disease causing?

A

Yes they are pathogens

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22
Q

What are the two types of Thermophiles?

A

Thermophiles
Hyperthermophiles

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23
Q

What temperature can thermophiles NOT grow at?

A

Any temperature below 45 degrees celsius

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24
Q

What are thermophiles optimum temperature?

A

50-60 degrees celsius

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25
Q

What is the maximum temperature thermophiles can grow at?

A

70-80 degrees celsius

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26
Q

Are thermophiles disease causing?

A

No, they are non-pathogenic

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27
Q

What temperature can hyperthermophiles NOT grow at?

A

Any temperature below 45 degrees celsius (same as thermophiles)

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28
Q

What are hyperthermophiles optimum temperature?

A

50-60 degrees celsius (same as thermophiles)

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29
Q

What is the maximum temperature hyperthermophiles can grow at?

A

110-121 degrees celsius

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30
Q

Are hyperthermophiles disease causing?

A

No, they are non-pathogenic

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31
Q

how does pH affect prokaryotes growth?

A

Too basic or too acidic will denature stop the bacteria from growing

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32
Q

What the pH range that most bacteria grow best in?

A

ph 6.5- 7.5 (neutral)

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33
Q

What are acidophiles?

A

Bacteria tolerable to acidity (low pH)

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34
Q

How does osmotic pressure affect cell growth?

A

Too little or too high concentrations of solute concentrations can inhibit growth

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35
Q

How does a hypertonic environment affect cell growth?

A

The solution/environment has higher concentration of solutes then inside the cell causes water to leave the cell and makes the cell shrink

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36
Q

What is isotonic?

A

Solute concentration outside the cell is equivalent to the solute concentration inside the cell

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37
Q

What is hypotonic?

A

Solute concentration outside the cell is lower than the solute concentration inside the cell

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38
Q

How do hypotonic/ low osmotic pressure affect cell growth?

A

Water enters the cell and microbes with weak cell walls with be lysed 9prevent growth)

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39
Q

How do high concentrations of sugar or salt affect cell growth?

A

Increase osmotic pressure = hypertonic
Water leaves the cell and prevent growth

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40
Q

How does energy extraction differ between aerobes and anaerobes?

A

Aerobes (use oxygen) extract more energy from nutrients

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41
Q

What are organisms that require oxygen for growth called?

A

Obligate aerobes

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42
Q

What enzymes do obligate aerobes have present?

A

Enzymes catalase and SOD

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43
Q

What does enzymes catalase and SOD do?

A

Neutralize toxic forms of oxygen

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44
Q

What are organisms that are anaerobic and aerobic called?

A

Facultative Anaerobes

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45
Q

Where do facultative anaerobes have greater growth?

A

In the presence of oxygen

46
Q

What enzymes do facultative anaerobes have present?

A

Enzymes catalase and SOD

47
Q

What is the name of organisms who only grow in the absence of oxygen?

A

Obligate Anaerobes

48
Q

What enzymes do obligate anaerobes have present?

A

NO enzymes
-cannot tolerate any form of oxygen

49
Q

What is the name of organisms who only grow in anaerobically but growth will continue in presence of oxygen?

A

Aerotolerant Anaerobes

50
Q

What enzyme do aerotolerant anaerobes have present?

A

Only SOD

51
Q

What occurs if only one enzyme is present?

A

Toxic forms of oxygen are partially neutralised

52
Q

What are organisms called that only grow in low oxygen concentrations?

A

Microaerophiles

53
Q

What happens if Microaerophiles are exposed to normal atmospheric oxygen?

A

They will produce lethal amounts of toxic forms of oxygen

54
Q

What bacteria are obligate aerobes?

A

Most bacteria

55
Q

What bacteria are obligate anaerobes?

A

Clostridium

56
Q

What is an example of a facultative anaerobe?

A

Escheria coli

57
Q

What kind of respiration do Aerotolerant anaerobes use?

A

Fermentation
-Obligate fermenters

58
Q

What is an example of an Aerotolerant anaerobe?

A

Lactobacilli

59
Q

What are example of microaerophiles?

A

Helicobacter pylori
Complyobacter jejuni

60
Q

What does Helicobacter pylori cause?

A

Stomach ulcers

61
Q

What does Complyobacter jejuni cause?

A

Gastroenterillis

62
Q

What are the toxic oxygen forms?

A

Singlet oxygen 1O2-
Superoxide Radicals or Anions (free radicals) O2-
Peroxide anion O2 2-
Hydroxyl radical OH-

63
Q

What is singlet oxygen?

A

Normal molecular oxygen that has been boosted into a higher-energy state
-Extremely reactive

64
Q

What are superoxide free radicals?

A

Very unstable (Steals electrons from neighbouring molecules and becomes a radical)

65
Q

What neutralises Superoide free radicals?

A

SOD: Superoxide dismutase

66
Q

What bacteria have SOD?

A

Obligate aerobes
Facultative anaerobes (when growing aerobically)
Aerotolerant anaerobes

67
Q

How does SOD neutralise superoxide free radicals?

A

SOD converts superoxide radical into molecular oxygen (O2) and hydrogen peroxide (H2O2)

68
Q

What is the reaction equation for SOD neutralising superoxide radicals?

A

O2- + O2- + 2H+ —> H2O2 + O2

69
Q

How are superoxide radicals produced?

A

Formed in small amounts during normal aerobic respiration or by obligate anaerobes in the presence of oxygen

70
Q

How are peroxide anions formed?

A

The hydrogen peroxide produced during the neutralisation of Superoxide radicals by SOD contains peroxide anions (produced during aerobic respiration)

71
Q

What has peroxide anions as an active principle?

A

Antimicrobial agents
e.g, Hydrogen peroxide and benzoyl peroxide

72
Q

What enzymes neutralises peroxide anions?

A

Enzyme catalase and peroxidase

73
Q

How does catalase neutralise peroxide anions?

A

Converts it into water and oxygen

74
Q

How does peroxidase neutralise peroxide anions?

A

Converts it into only water (no oxygen)

75
Q

What is the reaction equation for catalase?

A

2 H2O2 —> 2H2O + O2

76
Q

What is the reaction equation for peroxidase?

A

H2O2 + 2H+ —> 2H2O

77
Q

How are hydroxyl radicals formed?

A

Ionizing radiation and trace amounts are produced by most aerobic respiration

78
Q

What is the most reactive form of toxic oxygen?

A

Hydroxyl Radicals (OH)

79
Q

How are toxic oxygen forms important to phagocytosis?

A

When Phagocytes ingest pathogens the toxic forms kill them

80
Q

What is used to grow bacteria on a solid medium?

A

Nutrient agar

81
Q

At what temperature does Agar liquify?

A

100 degrees celsius

82
Q

At what temperature does Agar solidify?

A

37 degrees celsius

83
Q

What happens when the Agar is heated to 100 degrees?

A

Sterilization

84
Q

Why is sterilisation important fro culture media?

A

Allows it to be stored for longer periods

85
Q

Why is agar used?

A

Bacteria cannot metabolise it

86
Q

What is the name of the method when agar is used?

A

Streak plate method

87
Q

Why is the streak plate method used?

A

Isolates pure cultures
-Specific

88
Q

What is a pure culture?

A

Contains only one species or strain

89
Q

What is the tube/broth method?

A

Bacteria is grown in a nutrient broth in a test tube

90
Q

What are the pros and cons of the broth method?

A

Pro- Grows quickly
Con- Less specific (Can’t make a diagnosis

91
Q

What are the kinds of media?

A

Selective media
Differential media
Selective and Differential media

92
Q

What agar is used for selective media?

A

Bismuth sulfite agar

93
Q

What is the purpose of selective media?

A

Supresses unwanted microbes and encourages desired microbes
-only one colony appears

94
Q

What is an example of a bacteria encouraged to grow by selective media?

A

Salmonella typhus

95
Q

What does Salmonella typhus cause?

A

Typhoid fever

96
Q

What agar is used for differential media?

A

Blood agar

97
Q

What is the purpose of differential media?

A

Makes it easy to distinguish colonies of different microbes on the same plate

98
Q

What is an example of bacteria grown using differential media?

A

Streptococcus pyogenes
Invasive group A

99
Q

What does Streptococcus pyogenes cause?

A

Strep throat

100
Q

Why is blood agarused?

A

It contains RBC and can detect bacteria that lyses blood cells (Hemolysis)
Hemolysis will result in a clear zone

101
Q

What agar is used for selective and differential media?

A

Mannitol salt agar

102
Q

What is the purpose of using selective and differential media?

A

You suppress unwanted microbes and can distinguish colonies

103
Q

What is an example of bacteria grown using selective and differential media?

A

Staphylococcus aureus

104
Q

What does Staphylococcus aureus cause?

A

Skin infections, toxic shock and food poisoning

105
Q

what is binary fission?

A

method of cell division for microbial growth

106
Q

What is generation time?

A

Time required for a cell to divide (population doubles)

107
Q

What is the formula for generation time?

A

60 min x Hours / number of generations

108
Q

What is the lag phase?

A

Phase #1
Intense activity, population prepares for growth
no growth actually occurs

109
Q

What is log phase?

A

Phase #2
Logarithmic increase in population
Binary fission occurs

110
Q

What is the stationary phase?

A

Phase #3
Equilibrium
Microbial deaths are equal to production of new cells

111
Q

What is the death phase?

A

Phase #4
Logarithmic decline
Population decreases at logarithmic rate

112
Q
A

Microbiology- HLSC 124 🦠 (18 decks)

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