The Discovery of Archaea,
the 'Third Branch of Life', and Its Impacts

Resources with Additional Information

Electron micrograph and genetic map of Methanococcus jannaschii

'In 1996 scientists supported by the DOE's Microbial Genome Program reported the complete genome sequence of Methanococcus jannaschii, a methane-producing microorganism that dwells around "white smokers" on the seafloor.  The details of the genome confirm the existence of a third kingdom of living organisms, the Archaea (from the Greek word for "ancient"), distinct from other microbes lacking a cell nucleus, as well as higher plants and animals. ...

Shown ... is a photomicrograph of the microbe itself; [with] a depiction of its circular chromosome.  The two outer rings of colored lines show the predicted protein-coding regions.  The sequencing of M. jannaschii was prominently described in the New York Times and was chosen by Discover magazine as one of the two most important scientific discoveries of the year.'1

'Archaea look like bacteria, but biochemically and genetically, they are quite different. For example, archaea can thrive in extreme conditions that would kill other life forms. In the late 1970s, these unusual organisms were first recognized as distinct from eukaryotes (plants, animals, and other organisms whose cells have a nucleus) and prokaryotes (or bacteria, whose cells contain no distinct nucleus). ...  About two-thirds of the genes of M. jannaschii ... looked like nothing seen before in biology. The genes involved in energy production, cell division, and metabolism were similar to those in bacteria, whereas those involved in DNA transcription, translation, and replication were similar to those found in eukaryotes.'2

Resources with Additional Information

Additional information about Archaea (Methanococcus jannaschii) is available in documents and on the Web.

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