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Two Views of Life’s Organization – Domains
and Kingdoms
Domain Archaea
• Archaea means “early” or “primitive”. It is
believed that archaea evolved from some of the
first living organisms on Earth.
• Archaea look very similar to bacteria and were
originally classified as a type of bacteria.
• However, biochemical and genetic information
has now revealed that archaea are as different
from bacteria as they are from plants and
animals. Therefore, archaea are now grouped
into a kingdom of their own.
Prospecting for Archaea in Yellowstone’s Obsidian Pool
Although Archaea were first discovered in extreme environments, it’s
important to realize they’re found everywhere, not just in harsh conditions.
Characteristics
• Archaea do not
require oxygen to live
and are referred to as
anaerobic organisms.
• They do not perform
photosynthesis.
Instead Archaea obtain
their energy from
inorganic molecules or
from the Sun.
Characteristics continued
– Some thermophiles oxidize sulphur found in
hot springs
– Methanogens grow on carbon dioxide and
hydrogen gas found in deep sea vents and in
the intestines of other mammals.
A Deep Sea Thermal Vent – Prime
Habitat for Archaean Extremophiles
Prismatic Pool, Yellowstone Park – Another “Hot” Site for Archaean
Extremophiles
Roles and Uses
• Methanogens help digest sewage and oil spills,
producing methane, which can be used as an
alternative energy source
• Halophiles are used in cancer research
• Enzymes produced by archaea used in food
processing, perfume manufacturing and
pharmaceuticals
• The most famous archaea enzyme is the one obtained
from Thermus aquaticus. It is used in many scientific
laboratories to make more copies of small samples of
DNA