Archaeal Diversity Flashcards
1
Q
Archaea
A
Prokaryotes representing one domain in the tree of life
- Most species are adapted to extreme conditions (“extremophiles”)
2
Q
The Two Major Phyla of Archaea
A
- Euryarchaeota
- Crenarchaeota
3
Q
Outermost Structure: S-layer
A
- Composition: (glyco)protein
- Structure: 2D crystalline array
- Role in cell shape (?)
4
Q
Cell Wall: Pseudomurein
A
- Not always present
- Heteropolymer (disaccharide-peptides)
- Similar to bacterial peptidoglycan
5
Q
Archaea cell walls are resistant to…
A
- Lysozymes
- Most antibiotic targeting bacterial peptidoglycan synthesis
6
Q
Cytoplasmic Membrane
A
- Phospholipids contain NO fatty acids, but isoprenes instead
- Phospholipids ether; not ester linked
7
Q
Archaea membranes are…
A
- More stable than bacterial ones
- Present as monolayers or bilayers (or a mixture of both)
8
Q
Chromosome Organisation and Replication
A
- Circular chromosome (+ plasmids)
- Histones
- Multiple replication origins
- Encode polymerase B (Eukarya) and D (specific to Archaea)
9
Q
Transcription and RNA processing
A
- A single RNA pol exist, similar to eukaryotic RNA pol II
- Presence of introns
- Genes are organised in operons
10
Q
Translation
A
- Translation is coupled to transcription
- It involves several translation factors, like in Eukarya
- Ribosomes are 70S particles
11
Q
Physiology
A
- Very diverse; reflects a wide range of habitats
12
Q
(Hyper)thermophiles
A
- Include Crenarchaeota and Euryarchaeota
- High growth temperature (80-120 degrees Celsius)
- Most require elemental sulphur for growth
- Often acidophiles (pH 1-3)
13
Q
Halophiles
A
- Most Euryarchaeota (few bacteria and eukaryotes)
- Found in evaporating ponds, the Dead Sea and Great Salt Lake
- Require up to 5M NaCl for growth (0.6M in sea water!)
14
Q
Methanogens
A
- Euryarchaeota
- Found in anaerobic environments (rumen, gut, marine sediments)
- Use acetate/formiate/CO2 as electron acceptors
