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What are the 2 major phyla of Archaea?
euryarcheota and crenarcheaota
What types of conditions are most species adapted to? What is this termed?
extreme ones
extremophiles
Which taxonomic group of Archaea ?
one domain in the tree of life
Do Archaea have an s layer?
yes!
What’s the role of s layers in bacteria?
thought to be a role in cell shape - cell envelope integrity and viability
What does ultrastructure of an organism mean?
way to study the architecture of its cells and organelles
What makes up the ultrastructure of Archaea?
s layer
no cell wall
cytoplasmic membrane
Is pseudomurein present in all Archaea?
no, in fact quite rare
What are Archaea cell walls resistant to?
lysosymes
most antibiotic targeting bacterial peptidoglycan synthesis like penicillin (bc of pseudomurein)
What is the structure of pseudomurein in Archaea similar to?
bacterial peptidoglycan
What is the function of Archaellum in Archaea similar to? How do they differ?
flagella
how they are formed and structured, archaellum form from the base of the cytoplasmic membrane
Name 2 functions of hooks in Archaea?
link up between cells
colonise and hook onto elements of the env.
What are cannulae’s role?
How does the cytoplasmic membrane differ from bacterial ones in Archaea?
phospholipids don’t contain any fatty acids
phospholipids contain isoprenes
phospholipids have ether NOT ester linked
single leaflet or bilayer
How does the stability of Archaea membrane compare to that of bacteria?
more stable in Archaea
Are Archaea membrane monolayers or bilayers?
either or both
How are chromosomes organised?
circular chromosomes (+ plasmids) with histones
How do chromosomes replicate?
through multiple replication origins and polymerases B (also in Eukarya) and D (specific to Archaea)
Are there similarities between Archaea structures and those in Eukarya/Bacteria?
many, hints towards genetic/evolutionary links
How do transcription and RNA processing occur in Archaea?
single RNA polymerase is responsible like Pol2 in eukarya
introns
genes organised in operons
How does translation occur in Archaea?
→ Translation coupled to transcription
→ several translation factors, like in Eukarya
→ Ribosomes are 70 S particles
What explains the vast diversity of Archaea physiology?
wide range of their habitats (volcanos, antarctica etc) - will have form adapted to their way of getting energy, carbon etc
Where were acidianus infernus first found? What type of Archaea are they? What conditions do they require?
geothermic hot spring
Crenarchaeota hyperthermophile
75C, sulfur, 2.5 pH - not ideal to grow (very very hard and unpleasant)
What are 3 subtypes of Archaea and what distinguishes them?
hyperthermophiles
halophiles
methanogens
What is an application of Acidianus infernus explaining funding of its research?
important in oil industry, increases cost of refining oil
Are conditions to grow Archaea simple or complex?
VERY complex, specific and annoying
Where are halophiles found? What explains this?
evaporating ponds, Dead sea, Great Salt Lake
require up to 5M NaCl for growth (0.6M in seawater!)
What’s an example of Halophile? Where are they found and what are their ideal env. conditions?
Halobacterium halobium
Prevalent species in Great Salt Lake (4M salt); optimal growth at 75°C/pH 2.5-3
Are Halophiles easy to grow in labs?
easier, main thing is adding salt and making it a bit hotter
Are all halophiles euryarchaeota?
mainly but also a few bacteria and eukaryotes
Where are methanogens found? Why are they being studied particularly?
Found in anaerobic environments (rumen, gut, marine sediments…)
major role in global warming
What’s an example of methanogen? Where are they found and how do they grow?
Methanopyrus kandleri
Isolated in deep ocean on hydrothermal vent
Optimal growth at 105-115°C + high pressure needed
Why are Methanobrevibacter smithii heavily studied? What are their role?
found in human gut - interest with obesity studies
removal of bacterial end products of fermentation
What distinguishes cell ultrastructure in Archaea from in Bacteria?
A large number of Archae have an S-layer, but no cell wall
Archae cell wall is made of pseudomurein instead of peptidoglycan
The composition of the cytoplasmic membrane is special
Which properties of genome replication and expression are shared between Archaea and Eukarya?
→ Chromosome organisation and replication
→ Transcription
→ Translation
