Mesnage - Archaeal Diversity

Question 1

are archaea eukaryotes or prokaryotes?

Answer 1

prokaryotes

Question 2

which 2 major phyla make up archaea?

Answer 2

euryarchaeota and crenarchaeota

Question 3

most archaea are adapted to extreme conditions, what term is used to describe this?

Answer 3

extremophiles

Question 4

describe the ultrastructure of archaea

Answer 4

s-layer
cell wall (pseudomurein);
- isnt always present but if it is
-heteropolymer saccharides and polypeptides
-similar to peptidoglycan
-resistant to lysozymes/most antibiotics that target bacterial peptidoglycan synthesis
cytoplasmic membrane;
-phospholipids contains no f/a’s (contain isoprenes)
-phospholipids ether bond not ester bond

Question 5

name the differences in chromosome organisation between archaea and bacteria

Answer 5

circular chromosome + plasmid (same as bac)
histones (bac doesnt)
multiple replication origins
encode DNA polymerase B (eukarya) and DNA polymerase D (specific archaea)

Question 6

name the differences in transcription and RNA processing between archaea and bacteria

Answer 6

single RNA pol, similar to euk RNA pol II
has introns
genes organised in operons (same as bacteria)

Question 7

name the differences in translation between archaea and bacteria

Answer 7

coupled to transcription (same as bacteria)
involves several TF’s (transcription factors)
ribosomes are 70s particles (same as bacteria)

Question 8

name and describe the 3 major groups of archaea

Answer 8

1) hyperthermophiles: - include crenarchaeota and euryarchaeota
- high growth temperature
- must require sulfur for growth
- often acidophiles
2) halophiles: - mostly euryarchaeota (few bacteria and eukaryotes
- found in v. salty environments (require more than 5M)
3) methanogens: - euryarchaeota
- found in anaerobic environments (e.g. the gut/marine sediments)
- use acetate/formiate/CO2 as electron acceptor (CO2 + 4H2 => CH4 + H2O)