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Name: Susan C.
Status: Other
Age: 30s
Location: N/A
Country: N/A
Date: 2002

What characteristics make the Archaea bacteria different enough from the rest of the bacteria to justify placing them in a separate kingdom? Is it due to the diversity of the group (cell wall and can stand extreme temperatures?).

The grouping of bacteria into clusters that should represent evolutionary lineage is called phylogeny. Phylogeny can be based on different data. Commonly used is the sequence of the genes encoding the RNA parts of ribosomes (the cellular particles responsible for protein production). These RNA genes are highly conserved, but vary significantly between the clusters of the phylogenetic tree as we know them, including the separation of archae with the other bacteria. But other genes or other characteristics can also be used for phylogeny, and it is reassuring to see that the trees generated with different input data frequently correlate with the RNA trees. That indicates that we're on the right track. Though the details of such trees often vary, and can be the reason for serious debates, the position of the archeans and the rest of the bacterial world is generally not disputed.

If you are interested in bacterial phylogeny, or taxonomy, have a look at a magnificant web site: the Tree of Life. ( It also includes the eukaryotes, including animals and plants. It is a pleasure browsing in there.

Trudy Wassenaar

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