I am a very avid supporter of Olivia Judson’s wonderful science blog over at the New York Times (click on the link above). Today she salutes archaea, the third domain of the tree of life. These microbes are both ubiquitous and in many senses unexplored territory as far as biology is concerned–they’re difficult to culture in the laboratory.
More diagnostic: archaeal cell membranes have a different structure and composition from those of bacteria or eukaryotes. And although archaea organize their DNA much as bacteria do (they also have no cell nucleus, for example), many aspects of the way the DNA gets processed are distinctly different. Instead, the processing is more similar to what goes in within eukaryotic cells. Archaea also have large numbers of genes that are not found in the other groups.
Discoverers and Discoveries 