Domain: Archaea

Studies on 16S ribosomal RNA sequences by Carl Woese and colleagues
allowed the construction of phylogenetic trees for the procaryotes, showing
their evolutionary relatedness.

The work of Woese also revealed that one group of procaryotes differed
from all the others.

the Archaea are now regarded as being quite distinct from the Bacteria
(sometimes called Eubacteria).

Together with the Eucarya, these form the three domains of life.

archaea share some features in common with other bacteria and some with
eucaryotes. Extending nucleic acid analysis to other genes has shown that
members of the Archaea pos- sess many genes not found in any other type
of bacteria.
The domain is the high- est level of taxonomic grouping.