They are unusual because they assemble a network of tiny tubes outside of themselves. The archaea cells live in the spaces between the tiny tubes, and the colonies of archaea and tubes look like flakes in the liquid where they're growing. Here's a nice site: archaea.
What are archae or archaebacteria? How do they get their food? Where are they found? Some Euryarchaeota are methanogens living in anaerobic environments such as swamps. This form of metabolism evolved early, and it is possible that the first free-living organism was a methanogen. A common reaction in methanogens involves the use of carbon dioxide as an electron acceptor to oxidize hydrogen. Methanogenesis uses a range of coenzymes that are unique to these archaea, such as coenzyme M and methanofuran.
Other organic compounds such as alcohols, acetic acid, or formic acid are used as alternative electron acceptors by methanogens. These reactions are common in gut-dwelling archaea. Acetotrophic archaea also break down acetic acid into methane and carbon dioxide directly. These acetotrophs are archaea in the order Methanosarcinales, and are a major part of the communities of microorganisms that produce biogas. Other archaea, called autotrophs, use CO 2 in the atmosphere as a source of carbon, in a process called carbon fixation.
In addition, the Crenarchaeota use the reverse Krebs cycle while the Euryarchaeota use the reductive acetyl-CoA pathway. Carbon—fixation is powered by inorganic energy sources. Phototrophic archaea use sunlight as a source of energy; however, oxygen—generating photosynthesis does not occur in any archaea. Instead, in archaea such as the Halobacteria, light-activated ion pumps generate ion gradients by pumping ions out of the cell across the plasma membrane.
This process is a form of photophosphorylation. The ability of these light-driven pumps to move ions across membranes depends on light-driven changes in the structure of a retinol cofactor buried in the center of the protein. Besides these, archaeal energy sources are extremely diverse, and range from the oxidation of ammonia by the Nitrosopumilales to the oxidation of hydrogen sulfide or elemental sulfur by species of Sulfolobus, using either oxygen or metal ions as electron acceptors.
Archaea usually have a single circular chromosome, the size of which may be as great as 5,, base pairs in Methanosarcina acetivorans, the largest known archaean genome. One-tenth of this size is the tiny , base-pair genome of Nanoarchaeum equitans, the smallest archaean genome known. It is estimated to contain only protein-encoding genes.
Smaller independent pieces of DNA, called plasmids, are also found in archaea. Plasmids may be transferred between cells by physical contact, in a process that may be similar to bacterial conjugation. Plant species range from the tiny green mosses to giant trees. Without plants, life on Earth would not exist! Plants feed almost all the heterotrophs organisms that eat other organisms on Earth.
The animal kingdom is the largest kingdom with over 1 million known species. All animals consist of many complex cells. They are also heterotrophs. Members of the animal kingdom are found in the most diverse environments in the world.
To their surprise they discovered unicellular one cell organisms in the samples. These organisms are today classified in the kingdom, Archaebacteria. Archaebacteria are found in extreme environments such as hot boiling water and thermal vents under conditions with no oxygen or highly acid environments.
The biologists pictured above are immersing microscope slides in the boiling pool onto which some archaebacteria might be captured for study.
Like archaebacteria, eubacteria are complex and single celled. They are the kinds found everywhere and are the ones people are most familiar with. Eubacteria are classified in their own kingdom because their chemical makeup is different. Most eubacteria are helpful. Some produce vitamins and foods like yogurt.
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