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Classifying Living Things: The Domain Archaea
What features distinguish archaea from
other life forms?
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Thermal vents, home
of some Archaea
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The domain Archaea contains many organisms that
are not very well characterized. Archaeans are prokaryotic, single-celled
organisms. Their cells have a cell wall, but it is not made of
the same substances found in the cell walls of plants, fungi, and bacteria.
Despite lacking the organelles and nuclei seen in eukaryotic
cells,
the archaea are actually not that similar to bacteria. In fact,
based on their DNA and various fundamental cell processes, they are
more
closely related to eukaryotic organisms.
Most archaea do not make
their own food. Many absorb their food sources, in a similar
way to bacteria. Archaeans that do make their
own food do not make it through photosynthesis — that is, using
carbon dioxide, water, and the sun’s energy. They may use other
sources of carbon found in the environment, and chemicals for
energy rather than light.
How are archaea important to people?
Archaea were initially discovered in extreme,
inhospitable environments like hot springs and deep-sea hydrothermal
vents. We now know they occur in a diversity of environments, including
cow guts, where they produce methane, and many aquatic ecosystems.
Techniques in molecular biology are revealing a striking diversity
of archaea in many habitats. Unlocking the mystery of what they are
and how they are transforming their environment is proving to be a
very exciting challenge for microbiologists.
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