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AID > Microbiology > Flashcards

Microbiology Flashcards

1
Q

What is microbiology?

A
  • Study of things too small to be seen with the naked eye
  • Studying bacteria, fungi, archaea and protoza
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2
Q

What are the three domains of life?

A

Archaea, bacteria, eukaryota

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3
Q

How big are bacteria?

A

1-6 micrometers

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4
Q

Why can you see some bacteria with the naked eye?

A

Some accumulate stuff in their vacuole so are larger

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5
Q

What temperature must it be for microorganisms to survive?

A

Below 140 degrees Celsius

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6
Q

How many human and bacteria cells are in a person?

A

-10 ^13 human cells
-10 ^14 bacteria cells

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7
Q

How many microbial cells are there on earth?

A

About 4-6 x 10 ^30

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8
Q

What do archaea produce?

A

Methane, therefore they are different to others

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9
Q

What conditions do archaea need to grow?

A
  • High temperature
  • High pressure
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10
Q

Where are archaea found?

A

In all soil, they make up 5-10% of the community in the environment. The first archaea was isolated in 2004.

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11
Q

What are fungi?

A
  • Largest organism on the planet
  • Largest colony is 10,000 kg
  • Size varies
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12
Q

What are protists?

A
  • Most eukaryotes
  • Very diverse
  • 1-150 micrometers
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13
Q

Why are bacteria and archaea important to us?

A
  • Major portion of biomass on earth
  • Key reservoirs of all nutrients of life
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14
Q

Why are there so many bacteria? (5 reasons)

A
  • Rapid growth rate (2x humans)
  • Speciation
  • Long evolutionary history
  • Every niche is occupied
  • Lateral gene transfer
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15
Q

What is a phototroph?

A

Needs energy from light

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16
Q

What is a chemotroph?

A

Needs energy from chemical bonds

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17
Q

What is an organotroph?

A

Use organic compounds as electron donors

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18
Q

What is a lithiotroph?

A

Uses inorganic compounds as electron donors

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19
Q

What is a autotroph?

A

Uses CO2 as a carbon source

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20
Q

What is a heterotroph?

A

Uses organic compounds (plants and animals) as a carbon source

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21
Q

What are the primary nutrients that all organisms need?

A
  • Macronutrients
  • Micronutrients (trace metals)
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22
Q

What do phototrophs produce?

A

All 20 amino acids

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23
Q

What are fastidious bacteria?

A

They cannot produce all 20 amino acids, they need organic components

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24
Q

Where can microbes been grown?

A
  • Eukaryotic cells
  • Animals
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25
Q

In what method do bacteria grow?

A
  • Binary fission
  • Asexually
  • Exponential growth
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26
Q

What stops too many bacteria cells from growing?

A

Carrying capacity, it stops growth due to limited space and nutrients

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27
Q

How can we measure bacterial growth?

A
  • Turbidimetry
  • Haemocytometry
  • Dilution planting
  • Estimating no. of cells
  • Cloudy mediums
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28
Q

What are the 4 phases of bacterial growth?

A
  • Lag phase
  • Log phase
  • Stationary phase
  • Death phase
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29
Q

What is the difference between selective media and differential media?

A
  • Selective media grows specific types of bacteria
  • Differential media is based on growth and appearance, it can determine if something is pathogenic
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30
Q

What is a method of enzyme activity testing?

A

ApiZym - optimised to pathogens

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31
Q

What is the surface origin hypothesis?

A

There was a warm little pond which had the nutrients for life, there was no o zone layer and therefore hotter

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32
Q

What is the subsurface origin hypothesis?

A

There are hydrothermal vents at the ocean floor which have more stable conditions which a constant source of energy through redacted inorganic compounds

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33
Q

Which hypothesis for cellular life is more likely?

A

Subsurface origin hypothesis

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34
Q

What are phylogenies methods used for?

A

To allow us to determine how related organisms are to each other

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35
Q

What are the two phylogenetic methods?

A
  • Marker molecules (must be universal and in variable and condensed regions)
  • Analysing DNA sequencing
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36
Q

How old are eukaryotes?

A

2.5 billion years old

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37
Q

What are the two theories of evolution of eukaryotes?

A
  • Ancestor of mitochondrion, Nucleus formed, Ancestor of chloroplast (more likely)
  • Nucleus formed, Ancestor or mitochondrion, Ancestor of chloroplast
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38
Q

What did early life use as energy?

A

They used simple compounds (H2 and CO2), and broke down acetate to 2 carbons to produce methane and CO2 using archaea

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39
Q

What did oxygen in the atmosphere do for microorganisms?

A

Caused them to evolve into a oxygenic photo system using H2O

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40
Q

What are the roles of capsules?

A
  • Carbon store
  • Protection against desiccation
  • Can capture nutrients
  • Stops anti microbial and resist pathogens
41
Q

What is the difference between a capsule and a slime layer?

A
  • Capsules are organised, tight and not easy to remove
  • Slime layers are unorganised, easy to remove, hard to visualise and don’t stop small particles (not well understood)
42
Q

What is peptidoglycan made of?

A

Complex sugars (NAG, NAM)

43
Q

What is the structure of peptidoglycan?

A
  • Mesh like polymer
  • Arranged in dimmers (cross linked by amino acids to make amine bonds)
  • Strong to retain shape
44
Q

What is a gram +ve cell wall?

A
  • thicker than gram -ve
  • has teichoic acid
  • 90% of cell wall (25 sheets of peptidoglycan)
45
Q

What is a gram -ve cell wall?

A
  • little peptidoglycan
  • 10% of cell wall
  • between inner and outer membrane
46
Q

What does penicillin work on and why?

A

Inhibits PG synthesis during transpeptidation so stops cell wall synthesis meaning that cells lyse.
More effective on gram +ve bacteria

47
Q

What do lysozymes do?

A

They degrade 1,4 glycosidic bonds in PG backbone which makes cells sensitive to changes in osmotic pressure which is a defence against bacteria

48
Q

What is the structure of archaea cell walls?

A
  • no PG/ Meurin
  • some have pseudomeurin
  • contain polysaccharides, glycoproteins and S layers
  • not degrades by lysozymes and not sensitive to penicillin
49
Q

What do adhesion sites allow?

A

Transport to outer membrane and outside the cell

50
Q

What is Braun’s lipoprotein?

A
  • linked to peptidoglycan
  • embedded to outer membrane by hydrophobic end
51
Q

What are archaeal membranes?

A
  • different enzymes used
  • structure stabilises membrane at extreme pH and temp
  • different to bacterial and eukaryotic
  • hydrocarbons are attached to glycerol by ether links
52
Q

What are the components of the lipopolysaccharide (LPS)?

A
  • Lipid A
  • Core polysaccharide
  • O side chain
53
Q

What is the structure of Lipid A in the LPS?

A
  • 2 glucosamine residues linked to fatty acids and phosphate
  • integrated to membrane and projects out of cell
54
Q

What is the structure and function of the core polysaccharide in the LPS?

A
  • can induce an immune response
  • side chains of NAG, phosphate and ethanolamine
55
Q

What is the structure of the O side chain in the LPS?

A
  • variable region
  • O serotypes link to disease
  • Extends outwards from the cell
  • Flexible and bent
  • Variable composition
  • Rough/smooth depending on chain length
56
Q

What is the function of the LPS?

A
  • Stabilise membrane
  • Reduces permeability
  • Protects against host defences (rough more likely to be destroyed)
  • Key diagnostic tool
57
Q

What is the test used to test for endotoxins?

A
  • Rabbit pyrogen test
  • LAL assay
58
Q

What are endotoxins?

A
  • Can cause disease
  • Interact with immune system cells and release cytokines
  • Toxic in nanograms
  • Heat stable
59
Q

What are porins?

A

Channels that permit passage of small molecules, water filled channels are in the outer membrane

60
Q

What are some properties of porins?

A
  • Stable structure
  • Thermal stability
  • Homotrimeric
  • Most are non specific
  • Consists of 16 stranded antiparallel beta barrels
61
Q

What is the periplasm?

A

The space between the outer membrane and cytoplasmic membrane, works as a protein export. It has a gel like consistency.

62
Q

What are the two pathways that the periplasm uses?

A
  • sec pathway (folding of protein after translation)
  • TAT pathway (exports fully folded enzymes across the membrane)
63
Q

Name the three types of porters in the periplasm?

A
  • Uniporter (1 in 1 out)
  • Antiporter (1 in, diff out)
  • Symporter (2 in, 2 out)
64
Q

What is the structure of flagella?

A
  • rings are anchored to the membrane
  • shaft is removed by vigorous shaking
  • antigenic properties
  • motor driven due to transfer of protons through ring structure
65
Q

At what speed does flagella move?

A

300 rpm

66
Q

What is the order of flagella synthesis?

A
  • MS and C rings connect
  • Motor proteins join
  • P and L ring, hook and cap
  • Growth of filament
67
Q

Name the 4 types of flagella

A
  • Monotrichous
  • Amphitrichous
  • Lophotrichous
  • Peritrichous
68
Q

What are the two ways that flagella can move?

A
  • Run (motor goes ACW and filaments bundle)
  • Tumble (motor goes CW to twist)
69
Q

What is aerotaxis?

A

Movement towards O2

70
Q

What is chemotaxis?

A

Movement towards nutrients but away from toxins

71
Q

What is magnetotaxis?

A

Movement along lines of magnetism

72
Q

What is magnetotaxis?

A

Movement along lines of magnetism

73
Q

What is phototaxis?

A

Movement towards light

74
Q

How does bacteria behave under chemotaxis?

A
  • MCP senses change in environment
  • MCP interacts with sensor kinase CheA which can autophosphorylate
  • CheA phosphorylates CheY and binding changes the rotation
75
Q

What is gliding?

A

Moving without flagella and along the slime layer instead, adhesive molecules move laterally

76
Q

What is the structure of gas vesicles?

A

Protein vesicles which contain gas, mainly in planktonic bacteria and archaea

77
Q

What are gas vesicles used for?

A

Vesicles fill and empty depending on the needs to move to more oxygenated water or light (buoyancy)

78
Q

What is the function of fimbriae/ pili?

A
  • involved in genetic exchange between pili
  • pull bacteria close to sit on surface to allow penetration of the cell
  • allow pathogens to attach
79
Q

Which types of pili are the most important?

A

Type I and IV

80
Q

What is the structure and function of Type I fimbriae?

A
  • Fim F/ G/ H adhesion to fimbriae
  • Thin
    Works as an export system
81
Q

What is the structure and function of Type IV pili?

A
  • In gram -ve, in some +ve
  • Very thin
  • Long
    Aggregate laterally to form bundles which have twitching motility
82
Q

What are sex pilus?

A
  • 1-3 per cell
  • Helical arrangement
  • Invisible thread
83
Q

What are sex pilus used for?

A

They are required for gene transfer and attach via tip, they retract to bring cells together

84
Q

What are properties of bacterial endospores?

A
  • found in soil
  • heat resistant
  • only in gram +ve
  • 100,000 year life span
  • different shapes
  • disperse by wind, water and faeces
85
Q

How are bacterial endospores formed?

A

Formed inside the bacterial cell when a vegetative cell is stressed

86
Q

How long does sporulation take to complete?

A

8 hours (>200 genes involved)

87
Q

What triggers sporulation?

A

Nutrient depletion

88
Q

In what is the peptidoglycan cortex found?

A

Endospores

89
Q

Describe the resistance of endospores

A
  • 150 degree resistant
  • dehydration prevents denaturation
90
Q

Describe the 5 steps of germination

A

1) uptake of H2O and aa triggers germination
2) 30 min process
3) loss of refractile nature as it germinates
4) cell released and grows normally
5) gram -ve on release but becomes gram +ve again

91
Q

Name 5 barriers to infection

A
  • Lysozymes
  • Mucus
  • Skin
  • pH change
  • Flushing of urinary tract
  • Acidity in stomach
  • Phagocytes
  • Blood proteins
  • Cilia lining
  • Flora
92
Q

What is the ‘human microbiome’?

A

The ecological community of commensal, symbiotic and pathogenic organisms that share our body space

93
Q

What are health benefits of the human microbiome?

A

1) shield from pathogens
2) produce vitamins by bacteria

94
Q

What antibiotic was found in 1909?

A

Arsenic to treat syphilis

95
Q

What antibiotic was found in 1928?

A

Penicillin

96
Q

How many types of antibiotics are there?

A

5

97
Q

What did Jenner do?

A

In 1796 successfully found a vaccine for smallpox by infecting a child with cowpox

98
Q

What did Pasteur do?

A

In 1879 found the weakened vaccine

AID (4 decks)

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