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short note on archebacteria
Archaebacteria.

 They are ancient bacteria.While some archaebacteria are heterotrophic, the vast majority are chemo autotrophs, ie, they produce their own food from chemicals found in their environments. Based on the method by which they do this and the type of environment in which they are found, archaebacteria can be classified into four groups: methanogens, halophiles, sulfur reducers, and thermoacidophiles.

Found in harsh environments (undersea volcanic vents, acidic hot springs, salty water) Their cell walls  do not have peptidoglycan structure.


Methanogens

Live in anaerobic environments (no oxygen).
Obtain energy by changing H2 and CO2 gas into methane gas.
Found in swamps, marshes, sewage treatment plants, digestive tracts of animals.
Break down cellulose for herbivores (cows).
Produce marsh gas or intestinal gas (methane).

Extreme Halophiles

  Live in very salty water.
  Found in the Dead Sea, Great Salt Lake, etc.
Use salt to help generate ATP (energy).

Thermoacidophiles (Thermophiles)

Live in extremely hot  (1100C) and acidic (pH 2) water
Found in hot springs in Yellowstone National Park, in volcanic vents on land, & in cracks on the ocean floor that leak scalding acidic water

Sulfur Reducers

Like methanogens, sulfur reducers live near volcanic vents and pools. As their name suggests, they use the abundant inorganic sulfur found near these vents, along with hydrogen, as food. They also have very high heat tolerances, living in temperatures up to 85 degrees Celsius.

The structure of Archaebacteria varies greatly due to the extremely dissimilar environments among which these organisms range. While most have cell walls similar to those of the eubacteria, their composition differs greatly both from that of the eubacteria and between the different types of archaebacteria. Some methanogens have cell walls made of pseudopeptidoglycan, a molecule similar to the peptidoglycan that makes up eubacterial walls. The cell walls of other archaebacteria lack  pepitoglycan-like molecules and are made of polysaccarides, glycoproteins, or proteins.


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