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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