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BM211: Introduction to Microbiology > Block E Lecture 1: Archaea > Flashcards

Block E Lecture 1: Archaea Flashcards

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1
Q

Are archaea closer related to eukaryota or bacteria?

A

Eukaryota
(Slide 4)

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2
Q

What are 3 ways which the membranes of Archaea are different to that of bacteria?

A

They are more chemically and structurally diverse
They are semi-rigid lattice of pseudomurein, sugars, proteins or glycoprotein
They have no peptidoglycan layer
(Slide 7)

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3
Q

What are 4 ways in which Archaeal lipids are different from bacterial and eukaryotic lipids?

A

Archaea have ether-linked lipids as opposed to ester-linked lipids
Side chains are not fatty acids and are instead branched isoprene
They have a different form of glycerol (they have L-glycerol as opposed to D-glycerol)
Some Archaea possess lipid monolayers
(Slide 9)

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4
Q

What are 2 ways in which archaeal flagella are different from bacterial flagella?

A

Bacterial flagella are produced by the addition of flagellin subunits at the tip whereas archaeal flagella frow by the addition of flagella subunits to the base
Bacterial flagella are thicker and hollow allowing flagellin subunits to pass through
(Side 10)

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5
Q

What are the difference between bacterial RNA polymerases vs Archaeal and Eukaryotic RNA polymerases?

A

Bacterial RNA polymerase is simple vs Archaea and Eukaryotes having more complicated RNA polymerase
(Slide 11)

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6
Q

Do Archaea have plasmids?

A

Yes
(Slide 12)

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7
Q

Are Archaeal genes organised as operons?

A

Yes
(Slide 12)

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8
Q

Can Archaea act as pathogens?

A

No
(Slide 12)

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9
Q

Do Archaea package their DNA in histones?

A

Yes
(Slide 12)

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10
Q

What are the 5 major groups Archaea are split into?

A

Euryarchaeota
Crenarchaeota
Thaumarchaeota
Korarchaeota
Nanoarchaeota
(Slide 13)

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11
Q

What are Euryarchaeota?

A

A physiologically diverse group of Archaea with many inhabiting extreme environments
(Slide 14)

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12
Q

What is the class contained in the Euryarchaeota called?

A

Haloarchaea
(Slide 14)

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13
Q

What are the 3 key genera of Euryarchaeota?

A

Halobacterium, Haloferax and Natronobacterium
(Slide 14)

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14
Q

What conditions do Euryarchaeota require and why?

A

They require high salt concentrations as they are extremely halophilic
(Slide 14)

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15
Q

Where are euryarchaeota found?

A

Artificial saline habitats, solar salt evaporation ponds and salt lakes
(Slide 14)

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16
Q

How do euryarchaeota reproduce?

A

By binary fission
(Slide 14)

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17
Q

What are 2 features of most euryarchaeota?

A

Most are nonmotile and are obligate aerobes
(Slide 14)

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18
Q

How can euryarchaeota adapt to highly ionic life?

A

As their cell wall is composed of glycoprotein and is stabilized by sodium ions
(Slide 14)

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19
Q

What do extremely halophilic archaea need to maintain?

A

Water / osmotic balance
(Slide 16)

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20
Q

How do extremely halophilic archaea maintain water / osmotic balance?

A

Usually by accumulation or synthesis of compatible solutes
(Slide 16)

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21
Q

What do halobacterium species do to maintain osmotic balance?

A

They pump large amounts of potassium ions (K+) into the cell from the environment
(Slide 16)

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22
Q

How does halobacterium species pumping large amounts of potassium into the cell maintain osmotic balance?

A

As intracellular potassium ion (K+) concentration exceeds extracellular sodium ion (Na+) concentration and therefore a positive water balance is maintained
(Slide 16)

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23
Q

What are 2 features that proteins of halophiles have?

A

They are highly acidic
Contains fewer hydrophobic amino acids and lysine residues
(Slide 16)

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24
Q

What are some haloarchaea capable of?

A

Photosynthesis of ATP
(Slide 16)

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25
Q

What are methanobacteria?

A

A class in the euryarchaeota phylum which contains microbes which produce CH4 (methane), and are found in many diverse environments
(Slide 17)

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26
Q

What are the 3 main genera of methanogenic (methanobacteria) archaea?

A

Methanobacterium, Methanocaldococcus and Methanosarcina
(Slide 17)

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27
Q

What are the 4 different cell wall chemistries which methanobacteria can exhibit?

A

Pseudomurein (methanobacterium)
Methanochondroitin (Methanosarcina)
Protein or glycoprotein (Methanocaldococcus)
S-layers (Methanospirillum)
(Slide 18)

28
Q

Are methanobacteria obligate or facultative anaerboes?

A

Obligate
(Slide 18)

29
Q

What can convert substrates into methane?

A

Pure cultures of methanogens
(Slide 18)

30
Q

What reactions do methanobacteria need to use to convert other compounds which are not their substrates (e.g glucose) into methane?

A

Co-operative reactions between methanogens and other anaerobic microbes
(Slide 18)

31
Q

What phylum is the thermoplasmatales order in?

A

Euryarchaeota
(Slide 19)

32
Q

What are the 3 key genera of thermoplasmatales?

A

Thermoplasma, Picrophilus and Ferroplasma
(Slide 19)

33
Q

What extreme conditions do thermoplasmatales grow in?

A

They are thermophilic (high temp) and / or acidophilic (low pH)
(Slide 19)

34
Q

How do thermoplasma archaea produce energy?

A

They are chemoorganotrophs (obtains energy from the oxidation of reduced organic compounds)
(Slide 19)

35
Q

Are thermoplasma archaea facultative or obligate and are they aerobes or anaerobes?

A

They are facultative aerobes
(Slide 19)

36
Q

Where are thermophilic archaea found?

A

In self-heating coal piles
(Slide 19)

37
Q

What 2 unique cytoplasmic membrane structures have thermoplasma archaea evolved to maintain positive osmotic pressure and tolerate high temperatures and low pH levels?

A

Their membranes contain lipopolysaccharide-like material (lipoglycan) consisting of a tetraether lipid monolayer membrane with mannose and glucose

Their membrane contains glycoproteins but not sterols
(Slide 20)

38
Q

How do ferroplasma archaea generate energy?

A

They are chemolithotrophs (they gain energy from the oxidation of inorganic compounds)
(Slide 21)

39
Q

What extreme condition do ferroplasma archaea thrive in?

A

Acidic (low pH) conditions - making them acidophiles
(Slide 21)

40
Q

What do ferroplasma oxidise and what does this generate?

A

They oxidise Fe2+ to Fe3+, which generates acid
(Slide 21)

41
Q

Where do ferroplasma archaea grow?

A

In mine tailings containing pyrite (FeS2)
(Slide 21)

42
Q

What pH do picrophilus archaea grow optimally at and what does this make them?

A

They grow optimally at pH 0.7 which makes them extreme acidophiles
(Slide 21)

43
Q

What are picrophilus archaea model microbes for?

A

Extreme acid tolerance
(Slide 21)

44
Q

What phylum are thermococcales (order) and methanopyrus (genus) in?

A

Euryarchaeota
(Slide 22)

45
Q

What are the 2 key genera in the thermococcales order?

A

Thermococcus and Pyrococcus
(Slide 22)

46
Q

What are the thermococcus, pyrococcus and methanopyrus genera?

A

Three phylogenetically related genera of hyperthermophilic euryarchaeota
(Slide 22)

47
Q

Where do thermococcales and methanopyrus archaea live?

A

In anoxic (low/ no oxygen) thermal waters
(Slide 22)

48
Q

Are thermococcales and methanopyrus archaea motile or non-motile?

A

Highly motile
(Slide 22)

49
Q

Are Crenarchaeota obligate or facultative and are they aerobes or anaerobes?

A

Most are obligate anaerobes
(Slide 23)

50
Q

How do crenarchaeota generate ATP?

A

They can be chemolithotrophs or chemoorganotrophs with diverse electrons donors and acceptors
(Slide 23)

51
Q

Where are crenarchaeota found?

A

In extreme heat or extreme cold environments
(Slide 23)

52
Q

What are the 4 key genera of the crenarchaeota phylum?

A

Sulfolobus
Acidianus
Thermoproteus
Pyrobaculum
(Slide 24)

53
Q

Where do sulfolobus and acidianus archaea grow?

A

In sulphur-rich acidic hot springs
(Slide 24)

54
Q

Are sulfolobus archaea anaerobic or aerobic?

A

Aerobic
(Slide 24)

55
Q

What do sulfolobus archaea oxidize?

A

Reduced sulphur or iron
(Slide 24)

56
Q

What temperature do laboratory experiments with biomolecules suggest is the temperature limit for microbial life?

A

140 - 150°C
(Slide 25)

57
Q

What 2 protein factors limit microbial life at high temperatures?

A

Stability of protein monomers
Protein folding and thermostability
(Slide 25)

58
Q

How do thermophiles get around the stability of protein monomers?

A

Protective effect due to high concentration of cytoplasmic solutes
Use of more heat-stable molecules such as iron proteins instead of proteins that use NAD and NADH
(Slide 25)

59
Q

How do thermophiles get around the protein folding and thermostability constraints to be able to survive in high temperatures?

A

Proteins having highly hydrophobic cores and increased ionic interactions on protein surfaces help increase thermostability
(Slide 25)

60
Q

What 3 molecular restraints need to be surpassed in order for microbial life to be able to survive at high temperatures?

A

DNA stability
Lipid stability
Small Subunit (SSU) rRNA stability
(Slide 26)

61
Q

What are 4 ways in which thermophiles can surpass the DNA stability constraint in order to be able to survive in higher temperatures?

A

High intracellular solute levels stabilise DNA
Reverse DNA gyrase - introduces positive supercoils into DNA which stabilises it
High intracellular levels of polyamines stabilise DNA and RNA
DNA-binding proteins (histones) compact DNA into nucleosome-like structures
(Slide 26)

62
Q

How do thermophiles get around the lipid stability constraint in order to be able to survive at higher temperatures?

A

They possess dibiphytanyl tetraether type lipids which form a lipid monolayer membrane structure
(Slide 26)

63
Q

How do thermophiles get around the Small SubUnit (SSU) rRNA stability in order to be able to survive at higher temperatures?

A

They have a higher GC content, resulting in more hydrogen bonds and therefore a higher denaturation temperature
(Slide 26)

64
Q

The oxidation of what element is common to many hyperthermophiles?

A

Hydrogen
(Slide 27)

65
Q

What does the theory of hyperthermophiles being the closest descendants of ancient microbes suggest about their common oxidation of hydrogen?

A

That the oxidation of hydrogen may have been the first energy-yielding mechanism
(Slide 27)

BM211: Introduction to Microbiology (21 decks)

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