Archaeal diversity

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