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Microbiology > Topic 10 > Flashcards

Topic 10 Flashcards

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Biology 101 flashcards
1
Q

What are the physical requirements for microbial growth?

A
  • Temperature
  • pH
  • Osmotic pressure
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2
Q

What are the chemical requirements for microbial growth?

A
  • C source
  • N source
  • S source
  • P source
  • Organic growth factors
  • Trace elements
  • O2
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3
Q

What is the maximum growth temperature?

A

50 degrees Celcius

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4
Q

What is the optimum growth temperature?

A

approx 37 degrees Celcius

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5
Q

What is the minimum growth temperature?

A

approx 4 degrees Celcius

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6
Q

What temperature does Listeria monocytogenes grow at?

A

Low temperatures but growth is slowed

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7
Q

What plays a role in gastric ulcers?

A

Helicobacterpylori

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8
Q

What phile is Helicobacterpylori

A

Acidophile

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9
Q

What phile is Bacteria?

A

Neutrophile

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10
Q

What phile is Fungi?

A

Outside and inside Neutrophile

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11
Q

What pH can Helicobacter pylori withstand?

A

Low pH conditions

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12
Q

What happens in isotonic solution?

A

No water movement

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13
Q

What happens in hypertonic solution?

A
  • Water exits cell

ex: salt curing process

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14
Q

Carbon (Chemical Requirements)

A
  • For structural organic molecules

- Energy source

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15
Q

Nitrogen (Chemical Requirements)

A

In A.As, proteins

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16
Q

Sulfur (Chemical Requirements)

A
  • In A.As, thiamine, biotin

- 4% dry weight of cell

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17
Q

Phosphorus (Chemical Requirements)

A
  • In DNA, RNA, ATP, and phospholipids (membranes)

- 4% dry weight of cell

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18
Q

Organic Growth Factors (Chemical Requirements)

A
  • Organic compounds the organism cannot synthesize on its own
  • Usually not manufactured by the cell, must be obtained from environment
  • Ex: vitamins, A.A, nucleotides
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19
Q

Trace Elements (Chemical Requirements)

A
  • Inorganic elements required in small amounts, mostly for specific enzymes
  • Iron, Copper, Zinc, Magnesium, Calcium, etc
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20
Q

What are the oxygen requirements?

A

It may vary with the organism

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21
Q

What does oxygen do to energy generation?

A

It makes it more efficient however O2 can be lethal to some microbes

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22
Q

What are obligate aerobes?

A

They require oxygen for survival and growth

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23
Q

What are obligate anaerobes?

A

They cannot tolerate oxygen and cease to grow (and/or die) in the presence of oxygen

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24
Q

What are facultative anaerobes?

A

They can survive in aerobic and anaerobic conditions but prefer to grow in the presence of oxygen

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25
Q

What type of medium do you observe aerobic and anaerobic growth in?

A

Thioglycolate broth medium

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26
Q

What oxygen can cause a highly destructive tissue infection?

A

Clostridium perfringens, an obligate anaerobe

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27
Q

What are the two anaerobic culture methods?

A
  • “GasPak” anaerobic system (contains reducing media)

- Anaerobic glove box

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28
Q

How do microbes grow in nature?

A

Often grow as biofilms

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29
Q

How are microbes grown in the lab?

A

May be grown as mixed cultures or pure cultures

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30
Q

What does liquid media (broth) contain?

A

A.A, salts, and nutrients that microbes need to grow

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31
Q

What is liquid media (broth) used for?

A

To culture bacteria and yeast (and protists)

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32
Q

What can agar be added to?

A

Nearly added liquid media - used to culture bacteria, yeast, mould

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33
Q

How are microbes solidified?

A

Using agar

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34
Q

What is agar?

A

A carbohydrate extracted from seaweed

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35
Q

What is a colony?

A

When one cell multiplies

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36
Q

What can colony morphology tell us?

A

The # of different species based on colour (same colour might be a different species though)

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37
Q

Why is streaking done?

A

You dilute a sample so that a single bacterium will grow as a colony

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38
Q

What are the bacteria within a colony like?

A

They are clones (genetically identical)

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39
Q

Explains what happens by the 3rd and 4th streaks?

A

As you go back and forth you are spreading less and less bacteria (you are diluting the amount of bacteria)
Hopefully by the 3rd and 4th streaks you will have individual cells

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40
Q

How can you grow a colony?

A

Isolate a pure genetic sample on solid media if it is diluted so that a single bacterium will grow a colony

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41
Q

Why do you culture viruses?

A
  • To study virus particles

- Vaccine production

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42
Q

How do we culture viruses?

A
  • Viruses are obligate intracellular parasites (they can only grow in cells)
    Therefore we must culture them in cells and not on dish plates
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43
Q

Where are bacteriophages grown?

A

On bacterial lawns

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44
Q

What is a plaque?

A

A hole that a virus has destroyed all that bacteria (happens as the virus replicates)

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45
Q

Do bacteriophages cause problems for humans?

A

No

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46
Q

What can we grow in egg cultures?

A

Animal viruses

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47
Q

How can you grow animal viruses?

A

May be grown in cell culture

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48
Q

What are the easiest cells to grow?

A

Cancerous cells (because they are non-differentiated (ex: not nerve or muscle cells) and they continuously divide rapidly

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49
Q

How can you use cells to make a virus grow?

A

Inject the cells with virus and have the virus grow

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50
Q

Are cell lines maintained?

A

Continuous cell lines may be maintained indefinitely (these cells lines are ‘immortal’ i.e tumor cells)

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51
Q

How are cancer cells different from other cells?

A

They can divide even if they are touching each other

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52
Q

Cancer cells and immortality

A

Some cancer cells are immortal (turn on genes) they do not die, they keep dividing

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53
Q

What is chemically define media?

A

The chemical composition is precisely known

54
Q

What is an example of chemically defined media?

A

Minimal media

  • contains only the bare essentials
  • only certain species can grow
  • often used to study genetic mutants
55
Q

What is a type of non-selective media?

A

General or complex media

56
Q

What does general or complex media encourage?

A

The growth of a range of microbes

57
Q

What is complex media?

A

You are taking things and mixing things together but you don’t know the exact portion of things

58
Q

Describe enriched media (2)

A
  • Non-selective

- Contains additional factors needed to grow microbes with particular needs

59
Q

Describe selective media

A

Only supports the growth of specific microbes

60
Q

What type of cells does selective media allow to grow?

A

Gram (+) but not gram (-) cells

61
Q

How many species grow with selective media?

A

One species

62
Q

What grows on nonselective media

A

Everything grows

63
Q

What is an example of selective media?

A

Pseudomonas Isolation Agar

  • E.coli cannot grow
  • Pseudomonas aeruginosa can grow
64
Q

What conditions does fungi prefer?

A

Acidic

65
Q

What temperature does fungi and bacteria like?

A

Fungi grow at lower temperatures (25) whereas bacteria like higher temperatures (37), bacteria and fungi compete with each other

66
Q

Example of selective media (terms of bacteria or fungi)

A

pH of media may allow bacteria or fungi to grow

67
Q

What pH does bacteria like?

A

pH 7

68
Q

what pH does fungi like?

A

pH 6

69
Q

Why do different species have a different appearance?

A

It is due to the characteristics of the medium (differential media)

70
Q

How are X-gal and lactose related?

A

Anything that is capable of breaking down lactose can break down X-gal, it will break down and change colour

71
Q

What is a type of differential media?

A

Media containing X-gal

72
Q

How do blue colonies form?

A

When species/strains that can metabolize lactose (and X-gal) grow

73
Q

What is the difference between non differential and differential media

A

Non-differential media: everything looks the same

Differential media: Species show differing reactions

74
Q

What does EMB stand for?

A

Eosin methylene blue

75
Q

What type of media is Eosin ethylene blue (EMB)?

A

Differential media

76
Q

What does EMB media do?

A

Provides a colour indicator distinguishing between organisms that ferment lactose (eg. E. Coli) and those that do not (eg. Salmonella, Shigella)

77
Q

Growth and colour with EMB media

A

It does not restrict the growth of certain bacteria but it makes them look different

We will see different colours based on how well they get broken down

78
Q

What does MacConkey Agar contain?

A

Crystal violet, lactose, protein, and neutral red dye

79
Q

What does crystal violet prevent from growing?

A

Gram (+)

80
Q

What does crystal violet stick to?

A

Peptidoglycan therefore if you see growth it will be gram (-)

81
Q

What growth will you see on a MacConkey Agar plate?

A

E. Coli: Yes

Staph Aureus: No

82
Q

What growth will you see on a nutrient agar plate?

A

E. Coli: Yes

Staph Aureus: Yes

83
Q

What type of plate type is MacConkey Agar?

A

Selective and differential

84
Q

What happens if lactose is broken down on a plate?

A

There’s a colour change

85
Q

What 2 things can you figure out from growth on a MacConkey Agar plate?

A
  1. If we are dealing with gram (-) or gram (+)

2. If it is something that can break down lactose

86
Q

When is red dye present (MacConkey Agar)

A

Neutral red dye becomes red in the presence of the waste products of lactose metabolism - differential

87
Q

What occurs in Alpha (group B) in blood agar?

A

Break down and oxidation of hemoglobin

88
Q

What occurs in Beta cells (group A - streptococcus) in blood agar?

A

Capable of breaking down the RBCs completely, we are left with a clear area

89
Q

What occurs in Gamma (group D) in blood agar?

A

No breakdown

90
Q

What appearance do intact RBCs show in blood agar?

A

A nice overall red colour

91
Q

What appearance do broken RBCs show in blood agar?

A

They become clear and get clear around the cells (differential)

92
Q

What is enriched blood agar?

A

Blood supports additional microbes

93
Q

Blood agar and sheep blood

A

It contains 10-20% whole sheep blood

94
Q

What can you do in the hospital in terms of swabing?

A

There is an effective/rapid way to take swabs and get a sense of the diversity in the area and get a sense of the geno you are dealing with

95
Q

How fast does E.Coli divide?

A

Very quickly (every 20 mins)

96
Q

List the order of bacteria from fastest growing to slowest?

A
  • E.Coli
  • Staph Aureus
  • Mycobacterium TB
  • Mycobacterium leprae
  • Treponema pallidium
97
Q

How does bacterial replication occur?

A

Binary fission

98
Q

What happens during the lag phase (Bacterial Growth Curves)

A

Very little change in growth, lots of metabolic activity

99
Q

What happens in stationary phase (Bacterial Growth Curves)

A
  • Metabolic rate drops, build up wastes/toxins

- Nutrients used up

100
Q

What are the phases in Bacterial Growth Curves?

A
  1. Lag Phase
  2. Log (Exponential) Phase
  3. Stationary Phase
  4. Death Phase
101
Q

What happens in the log (exponential) phase in Bacterial Growth Curves?

A
  • Binary fission
  • Exponential growth
  • Very sensitive phase (ABX)
102
Q

What happens in the death phase in Bacterial Growth Curves?

A

Cell lysis (cell ruptures)

103
Q

What happens to cell division speed after the lag phase? (Bacterial Growth Curves)

A

It divides very quickly

104
Q

When are ABX quite effective to them?

A

Log phase (Bacterial Growth Curves)

105
Q

When are they going to compete against each other? (Bacterial Growth Curves)

A

Stationary Phase

106
Q

Why do the cell lyse during the death phase? (Bacterial Growth Curves)

A

They run out of food and waste builds up

107
Q

What are the steps of Virus One-step Growth Curve?

A
  • Attachement
  • Penetration
  • Biosynthesis/Maturation
  • Burst Time
108
Q

How can you measure microbial growth? (3 words)

A

Direct microscope count

109
Q

What is direct microscope count

A

Directly count the # of cells in a knwon volume using a counting chamber (hemacytometer)

110
Q

What is the advantage of direct microscope count?

A
  • Can give a good # of how many cells
  • Inexpensive
  • Don’t need special reagents
    (Traditional way but now it can be done with equipment)
111
Q

What is the disadvantage of direct microscope count?

A
  • Tedious

- May not be able to tell if the cells are alive

112
Q

How can you measure microbial growth? (2 words)

A

Plate count

113
Q

What is plate count?

A

The suspension of cells is mixed with or spread on agar

114
Q

What are the advantages of plate count?

A

Viable cells form colonies which are easily counted

115
Q

What are the two plate methods

A

The pour plate method and the spread plate method

116
Q

Which of the two plate methods are more popular?

A

The spread plate method

117
Q

Each colony is the product of ___

A

A single bacterium

118
Q

What is fecal coliform count?

A

Used to examine water samples for contamination due to human waste

119
Q

How is fecal coliform count done?

A

A water sample is passed through a filter which is then placed on selective media (which then grow as colonies)

120
Q

How can you measure microbial growth (T)

A

Optical Density (Turbidity)

121
Q

What is optical density (turbidity)?

A
  • Cells scatter and absorb light

- Shine light through a culture sample and measure how much is transmitted using a spectrophotometer

122
Q

What will the Sepctrophotometer tell us about cells?

A

They will tell us how many cells are present but will not tell us if they are alive or dead

123
Q

What is serial dilution?

A

Used if the sample is very concentrated (eg. if you were counting bacteria in a liquid culture)
- Are able to tell how many bacteria were in the original sample by working bacteria and tell the starting concentration

124
Q

In what factor does dilution work (Serial Dilutions)

A

Each time you are reducing the # of bacteria by a factor of 10

125
Q

How would you collect a sample of diseased tissue?

A

Surgical removal (biopsy)

126
Q

How would you collect a specimen from the lung?

A

Either sputum dislodged by coughing or acquired via a catheter

127
Q

How would you get a sample of urine?

A

Either sterile technique from a catheter or “clean catch” method when peeing which should be midstream

128
Q

How would you get a sample from the stomach?

A

Intubation (inserting a tube into the stomach or an NG)

129
Q

How would you get a sample of CSF?

A

Needle aspiration from subarachnoid space of spinal column

130
Q

How would you get a sample of blood?

A

Needle aspiration from vein; anticoagulants are including in the specimen tube

131
Q

How would you get a sample of skin?

A

Sterile swab brushed across the surface while not touching the neighbouring tissue

132
Q

What replication process is good if you are growing bacteria in the lab

A

Binary fission

Microbiology (13 decks)

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