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PHA112 > Microbiology 4 > Flashcards

Microbiology 4 Flashcards

1
Q

what is carbons % dry weight, its source and its function?

A

50%

  • organics / CO2
  • main constituent of cell, cell material and water
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2
Q

what is oxygens % dry weight, its source and its function?

A

20%

  • H2O, organics, CO2 and O2
  • electron acceptor in aerobic respiration
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3
Q

what is nitrogens % dry weight, its source and its function?

A

14%

  • NH3, NO3, organics, N2
  • amino acids, nucleotides & coenzymes
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4
Q

what is hydrogens % dry weight, its source and its function?

A

8%

  • H2O, organics, H2
  • organic compounds and cell water
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5
Q

what is phosphorous’ % dry weight, its source and its function?

A

3%

  • inorganic phosphates
  • nucleic acids, nucleotides & phospholipids
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6
Q

what is sulphurs % dry weight, its source and its function?

A

1%

  • SO4, H2S, S^o and organic sulphur compounds
  • proteins & several coenzymes
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7
Q

what is potassiums % dry weight, its source and its function?

A

1%

  • potassium salts
  • main inorganic cation & enzymatic cofactor
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8
Q

what is magnesiums % dry weight, its source and its function?

A
  1. 5%
    - magnesium salts
    - inorganic cation & enzymatic cofactor
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9
Q

what is calciums % dry weight, its source and its function?

A
  1. 5%
    - calcium salts
    - inorganic cation, enzymatic cofactors & endospores
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10
Q

what is irons % dry weight, its source and its function?

A
  1. 2%
    - iron salts
    - cytochrome component, enzymatic cofactor
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11
Q

carbon source trophs?

A
  • autotrophs

- heterotrophs

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12
Q

energy source trophs?

A
  • phototrophs

- chemotrophs

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13
Q

electron source trophs?

A
  • lithotrophs

- organotrophs

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14
Q

autotrophs?

A

CO2 sole / principle carbon source

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15
Q

heterotrophs?

A

obtained from other organism

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16
Q

phototrophs?

A

light

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17
Q

chemotrophs?

A

compound oxidation

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18
Q

lithotrophs?

A

reduced inorganic compounds

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19
Q

organotrophs?

A

organic molecules

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20
Q

what are the 2 ways to culture microorganism?

A
  • liquid media (broth)

- solid media (agar plates)

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21
Q

who was in vitro microorganism culture originally grown by?

A

koch (late C19th) on potato slices and gelatine

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22
Q

in liquid media, how do bacteria grow?

A

as individual cells until available nutrients exhausted

  • makes suspension of cells (can’t differentiate between different cell types without further testing)
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23
Q

on solid media, how does bacteria grow?

A

bacteria and fungi form colonies with distinctive appearances

  • each colony comes from single cells
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24
Q

what can the formula of media influence?

A

colony appearance (selective and differential media)

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25
Q

what is the difference between solid and liquid media?

A

solid has addition of gelling agent (agar)

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26
Q

undefined media?

A

contains chemically undefined yeast/veg/meat extracts and digested proteins

  • batch-batch variation and reproducibility
  • useful for routine growth applications
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27
Q

defined media?

A

(synthetic media) all components chemically define

  • highly reproducible
  • can = rich/minimal depending on requirements
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28
Q

obligate aerobe?

A

e.g. mycobacterium tuberculosis

cannot survive without oxygen

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29
Q

obligate anaerobe?

A

e.g. clostridium difficile

cannot survive in presence of oxygen

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30
Q

facultative aerobe?

A

e.g. staphylococcus aureus

can grow in presence of oxygen / produce energy by fermentation

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31
Q

microaerophile?

A

e.g. campylobacter jejuni

needs reduced oxygen content (inc CO2) in order to survive

32
Q

aerotolerant anaerobe?

A

e.g. streptococcus mutans

can tolerate oxygen in air but makes energy in fermentation

33
Q

what are the methods for anaerobic/aerotolerant culture?

A
  • anaerobic cabinet
  • gaspak sachets
  • candle extinction
34
Q

anaerobic cabinet?

A
  • big isolates cabinet
  • 95% N2, 5% H2 with palladium catalyst
  • under positive pressure
35
Q

gaspak sachets?

A

produces CO2 & H2 from breakdown of citric acid, cobalt chloride and NaBH4

36
Q

candle extinction?

A

uses up oxygen by burning of candle in jar

37
Q

what 2 methods rarely produce a true anaerobic enviro?

A

gaspak and candle methods

38
Q

most bacteria reproduce by binary fission, what do other reproduce by?

A

budding

39
Q

what is the generation time?

A

time taken to reproduce

40
Q

how does the generation time vary?

A
  • e.coli: 30 mins

- mycobacterium leprae: 14 days

41
Q

how many distinct phases are there in bacterial growth?

A

4

42
Q

lag phase

A
  • no immediate increase in cell number

- old cells depleted & need time for synthesis of new cell components/metabolites

43
Q

exponential (log) phase

A
  • growth & division at max possible rate five genetic potential & enviro conditions
  • regular doubling time
44
Q

stationary phase

A
  • in closed system nutrients = depleted & waste products build up
  • growth ceases (or balanced by death)
  • morphological and metabolical changes (e.g. secondary metabolism)
45
Q

death phase (senescence)

A
  • severe nutrient deprivation
  • build-up of toxic waste products
  • viable cell numbers decline at exponential rate
46
Q

primary metabolism

A

includes major metabolic pathways

  • energy production and release
  • cell component synthesis
  • enzyme production
47
Q

secondary metabolism

A

non-essential metabolic pathways

  • includes production of natural products e.g. antibiotics
  • production of secondary metabolites in disease states —> inc pathogenicity (e.g. pyocyanin)
48
Q

what kind of system are flask cultures?

A

closed systems

49
Q

flask/batch cultures

A
  • used for optimisation
  • nutrient availability limited
  • atmosphere limited due to diffusion at liquid surface
  • limited product production (not suitable for industry, lab scale only)
50
Q

what kind of systems are chemostats?

A

open systems

51
Q

chemostats/ continuous cultures

A
  • allows for highly controlled growth

- nutrients supplied at constant rate

52
Q

formula for steady state?

A

Mew = D = F/V

53
Q

what are the 3 growth modes in bulk culturing?

A
  • batch - full at start
  • fed batch - fill until vessel full
  • continuous - fill and overflow
54
Q

what is the important criteria in bulk culturing?

A
  • maintain adequate mixing
  • maintain high oxygen levels - if aerobic
  • control pH
  • control temp
  • control foam
  • initial starting conc
55
Q

what does viral replication rely on?

A

subversion of host replication machinery

in both prokaryotic and eukaryotic viruses

56
Q

in bacteriophages what does subversion lead to?

A
  • cell destruction

- lytic replication

57
Q

in eukaryotes what do viruses tend to do?

A

bud rather than destroy cell

e.g. influenza, HIV

58
Q

give examples of viruses which lie dormant and cause human disease?

A
  • herpes simplex virus

- human papilloma virus

59
Q

what is lysogenic replication?

A

when bacteriophages integrate genome into host and replicate alongside host

60
Q

what is evolution?

A

change in population over time

61
Q

how does evolution arise?

A
  • acquisition of new genes

- mutation of existing genes

62
Q

results of bacterial evolution can = good/bas

give examples of this?

A
  • inc product yield
  • become pathogenic
  • inc in resistance to treatment
63
Q

more complex the organism ….

A

slower rate of evolution

64
Q

what is a mutation and give examples of how mutations can arise?

A

permanent change in single cell (not necessarily cause any noticeable change/get passed on)

  • UV irradiation
  • chemical exposure
  • poor genome copy
65
Q

a harmful or deleterious mutation decreases…

A

organism fitness

66
Q

a beneficial/advantageous mutation increases ….

A

organism fitness

also include mutations that promote desirable traits

67
Q

what kind of effect does a neutral mutation have?

A

no harmful / beneficial effect

such mutations occur at steady state

68
Q

what are the 3 main mechanisms through which bacteria can evolve?

A
  • transformation
  • transduction
  • conjugation
69
Q

transformation?

A

direct uptake of DNA through cell membrane

70
Q

transduction?

A

introduction of genetic material via viral vector

71
Q

conjugation?

A

transfer of genetic material between 2 directly connected bacteria

72
Q

antibiotic usage can as what on bacteria?

A

selective pressure

removes competition for resistant cells by killing susceptible cells

73
Q

how can bacterial strains be improved naturally?

A

spontaneous mutation (random & infrequent)

74
Q

give examples how can exposure to mutagens increase frequency of mutations?

A
  • uv/chemical exposure
  • random mutagenesis
  • mutants can be picked and assessed for increased production
75
Q

what is targeted mutagenesis?

A

add/remove/alter genes to improve overall yield

76
Q

what is production measured in?

A

activity/mL

PHA112 (37 decks)

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