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Infection Biology and Microbiology > Lecture 1: Introduction to Microbiology > Flashcards

Lecture 1: Introduction to Microbiology Flashcards

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1
Q

What is microbiology?

A

The study of organisms that are too small to see with the naked
eye

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2
Q

What organisms are usually studied in microbiology?

A
  • Bacteria
  • Archaea
  • Fungi
  • Protozoa
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3
Q

Is it true that some of the organisms studied in microbiology aren’t actually that small?

A

Yes

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4
Q

Is the idea of there being ‘5 Kingdoms’ incorrect?

A

Yes, now it is commonly accepted that there are ‘3 domains’.

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5
Q

What was the 5 kingdom system replaced by?

A

The 3 domain system

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6
Q

What was included in the 5 kingdom system?

A
  • Plantae
  • Fungi
  • Animalia
  • Protista
  • Bacteria
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7
Q

What is the average size of bacteria?

A

1-6 µm

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8
Q

Is it true that some of the largest bacteria can be visible to the eye?

A

Yes

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9
Q

How do you convert micrometres to millimetres?

A

You divide by 1000

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10
Q

How large is Epulopiscium
fishelsoni ?

A

0.7 mm

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11
Q

How large is Thiomargarita
namibiensis ?

A

0.75 mm

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12
Q

Which bacteria is 0.7 mm in size?

A

Epulopiscium fishelsoni

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13
Q

Which bacteria is 0.75 mm in size?

A

Thiomargarita namibiensis

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14
Q

Was it once thought that all archaea were only extremophiles?

A

Yes

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15
Q

Why aren’t archaea and bacteria the same?

A

Because they are different to each other at the molecular level

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16
Q

Are there any known pathogenic archaea?

A

No

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17
Q

When was the first known non-extreme archaeaon located?

A

In 2004

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18
Q

Do the sizes of fungi vary a lot?

A

Yes

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19
Q

How much does the largest fungal colony weigh?

A

Around 10,000 kg

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20
Q

What are most eukaryotes?

A

Protists

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21
Q

What is Paramecium?

A

A ciliated protozoan

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22
Q

What is the size range of protists?

A

1-150 μm

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23
Q

What is the estimate of the total microbial cells on earth?

A

4-6 x 10³⁰ cells

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24
Q

What does microbial carbon equal?

A

That of all plants

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25
Q

What are major portions of biomass on earth?

A

Bacteria and archaea

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25
Q

Is it true that Microbial N and P is >10X that of plant biomass?

A

Yes

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26
Q

Why are there so many microorganisms?

A
  • Because they have a rapid growth rate
  • There’s many chances of speciation through random mutations
  • Due to the exchange of genetic material (lateral gene transfer)
  • Every available niche is occupied by specifically adapted
    microbes
  • Microbes have a very long evolutionary history (~3.8 billion years)
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27
Q

What does a phototroph do?

A

Obtains energy from light

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28
Q

What does a Chemotroph do?

A

Obtains energy from chemical bonds

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29
Q

What does an Organotroph do?

A

Uses organic compounds as e- donors

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30
Q

What does a Lithotroph do?

A

Uses inorganic compounds as e- donors

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31
Q

What do Autotrophs do?

A

They use Carbon dioxide as a Carbon source

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32
Q

What do Heterotrophs do?

A

They use organic carbon as a carbon source

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33
Q

What does a Photolithoautotroph do?

A
  • Uses light energy
  • Uses water as an electron donor
  • Fixes Carbon Dioxide
34
Q

Give examples of Photolithoautotrophs

A
  • Cynobacteria
  • Most plants
35
Q

What do Chemoorganoheterotroph do?

A
  • Obtain energy from chemical bonds
  • Use ogranic compounds as electron donors
  • Use organic carbon as a carbon source
36
Q

Give example of Chemoorganoheterotrophs

A
  • Escherichia coli
  • Animals
37
Q

What do Chemolithoautotrophs do?

A
  • They obtain energy from chemical bonds
  • They use inroganic compounds (reduced sulfur) as electron donors
  • They fix Carbon dioxide
38
Q

Give an example of a Chemolithoautotroph

A

Thiobacillus spp.

39
Q

What is needed for the growth of microorganisms in labs?

A

Macronutrients and micronutrients

40
Q

What are macronutrients

A

Carbon, either from Carbon dioxide or from Organic Carbon.

41
Q

What are micronutrients ?

A

Trace metals, such as Iron and Zinc

42
Q

What do Prototrophs do?

A

They synthesise all their own cellular components (including ALL amino acids, nucleotides, vitamins)

43
Q

What do Fasidious bacteria need in their growth media?

A

organic components, such as vitamins

44
Q

What is the Carbon and energy source in e coli?

A

Glucose

45
Q

What is the e coli medium dissolved in?

A

1 litre of distilled water

46
Q

What is the pH of the e coli medium adjusted to?

A

pH 7

47
Q

Does the e coli medium have any complex compounds?

A

No

48
Q

Why doesn’t the e coli medium have any complex compounds?

A

Because E. coli can make them all itself.

49
Q

How many different components does the Neisseria gonorrhoeae require?

A

35

50
Q

What is the source of glucose in the Neisseria gonorrhoeae medium?

A

Glucose

51
Q

Apart from the components, what else is needed in the Neisseria gonorrhoeae medium?

A
  • The many sterile components are mixed
  • Then the pH is adjusted to 7
  • Then the Neisseria gonorrhoeae is grown in 3-10 % Carbon dioxide.
52
Q

Describe the complex medium for E. coli and some Neiserria spp.

A
53
Q

How do bacteria grow?

A

By asexual reproduction, either through binary fission or budding

54
Q

Do bacteria grow exponentially?

A

Yes

55
Q

Do bacteria cells double in size, then split?

A

Yes

56
Q

What happens when bacteria don’t separate properly?

A
  • Pairs are produced
  • Larger assemblies of bacteria are produced
  • Both of these are problematic for the bacteria
57
Q

How quickly does e coli double ?

A

Once every 20 minutes

58
Q

What is the growth of bacteria limited by?

A

Space and availability of nutrients

59
Q

Which microbes grow differently?

A
  • Those that have very strict requirements for growth
  • Slow growing Anaerobes
60
Q

What happens in the lag phase?

A
  • Bacteria are adapting to the new condition of having nutrients available to them.
  • Genes are switched on, new proteins are made that enable them to grow
61
Q

What happens in the exponential phase?

A
  • Bacteria grow as fast as they possibly can
  • Straight line, as the number of microbes is being measured on a log scale
62
Q

why is the exponential phase a straight line?

A

because the number of microbes is being measured on a log scale

63
Q

What does the gradient of the exponential phase tell you?

A

How quickly the bacterial cells doubles in mass

64
Q

How can you work out how quickly bacterial cells double in mass?

A

By working out the gradient of the exponential phase

65
Q

What happens in the stationary phase?

A
  • Run out of nutrients.
  • There is a build-up of waste products which inhibits growth.
  • Too crowded to be able to make anymore cells and so the cells stop growing.
  • Many cell pathways are switched off.
66
Q

What happens in the death phase?

A
  • Cells start to die
  • Cells that are still living can utilise some of the energy that is released by the dying cells.
67
Q

What’s one way of counting bacteria cells?

A

Using haemocytometry, use grid and microscope to estimate how many cells there are in the culture.

68
Q

What’s one way of measuring optical density?

A

Using turbidmetry

69
Q

When do you measure how much DNA and protein is in the culture?

A
  • If the cells clump together so that you can’t measure optical density properly.
  • If the cells stick to the surface of the flask, rather than being in the liquid culture.
70
Q

What are the ways in which bacterial growth can be measured?

A
  • By measuring cell number
  • By measuring optical density
  • By measuring the fresh/dry weight
  • By measuring the amount of protein
  • By measuring the amount of DNA
71
Q

Do round bacteria scatter less or more light?

A

Less

72
Q

Do rod-shaped bacteria scatter less or more light?

A

More

73
Q

What is the problem with identifying microbes from one another when looking down a microscope?

A

They have a limited morphological diversity, and so most microbes look similar down a microscope

74
Q

What are some traditional ways of identifying microorganisms?

A
  • Microscopy and staining
  • Growth on selective/ differential media
  • Testing substrate spectrum supporting growth
  • Testing of enzyme activities (antibiotic resistance).
  • Characterisation of cell chemical constituents (lipids, cell wall components, DNA base ratio, quinones)
75
Q

Will some bacteria only grow on specific sugars?

A

Yes

76
Q

What is modern identification of microorganisms based upon?

A

The sequencing of specific conserved genes

77
Q

What does selective media allow to happen?

A

Selective media allows for the growth of only certain types of organism

78
Q

In diagnostic clinical microbiology, what is selective media used for?

A

Identifying presumed pathogens from clinical specimens.

79
Q

Does penicillin affect more gram negative or more gram positive bacteria?

A

More gram positive bacteria

80
Q

What does differential media allow to happen?

A
  • Differential media allows for the identification of organisms based on growth and appearance on that medium (often based on colour differences).
  • Used to determine if a culture is potentially pathogenic
81
Q

How can enzyme activities in bacteria be tested?

A
  • A culture of the organism is grown
  • The cells are resuspended in a buffer
  • The test wells are inoculated
  • The resulting colour in the test strip is compared against a database
  • This can help to distinguish between pathogenic and benign strains
82
Q

What test is commonly used for testing enzyme activity in microorganisms?

A

ApiZym

83
Q
A

Infection Biology and Microbiology (6 decks)

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