Title: Archaea - Wikipedia
Headings: Archaea
Archaea
Contents
Classification
Early concept
Classification
Cladogram
Taxonomy
Concept of species
Origin and evolution
Comparison with other domains
Relationship to bacteria
Relation to eukaryotes
Morphology
Structure, composition development, and operation
Cell wall and flagella
Membranes
Metabolism
Genetics
Gene transfer and genetic exchange
Archaeal viruses
Reproduction
Behavior
Communication
Ecology
Habitats
Role in chemical cycling
Interactions with other organisms
Mutualism
Commensalism
Significance in technology and industry
See also
References
Further reading
External links
General
Classification
Genomics

Content: organic compound turnover; and maintaining microbial symbiotic and syntrophic communities, for example. No clear examples of archaeal pathogens or parasites are known. Instead they are often mutualists or commensals, such as the methanogens (methane-producing strains) that inhabit the gastrointestinal tract in humans and ruminants, where their vast numbers aid digestion. Methanogens are also used in biogas production and sewage treatment, and biotechnology exploits enzymes from extremophile archaea that can endure high temperatures and organic solvents . Contents
1 Classification
1.1 Early concept
1.2 Classification
1.3 Cladogram
1.4 Taxonomy
1.5 Concept of species
2 Origin and evolution
2.1 Comparison with other domains
2.2 Relationship to bacteria
2.3 Relation to eukaryotes
3 Morphology
4 Structure, composition development, and operation
4.1 Cell wall and flagella
4.2 Membranes
5 Metabolism
6 Genetics
6.1 Gene transfer and genetic exchange
6.2 Archaeal viruses
7 Reproduction
8 Behavior
8.1 Communication
9 Ecology
9.1 Habitats
9.2 Role in chemical cycling
9.3 Interactions with other organisms
9.3.1 Mutualism
9.3.2 Commensalism
10 Significance in technology and industry
11 See also
12 References
13 Further reading
14 External links
14.1 General
14.2 Classification
14.3 Genomics
Classification
Early concept
Archaea were found in volcanic hot springs. Pictured here is Grand Prismatic Spring of Yellowstone National Park. For much of the 20th century, prokaryotes were regarded as a single group of organisms and classified based on their biochemistry, morphology and metabolism. Microbiologists tried to classify microorganisms based on the structures of their cell walls, their shapes, and the substances they consume. In 1965, Emile Zuckerkandl and Linus Pauling instead proposed using the sequences of the genes in different prokaryotes to work out how they are related to each other.