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Different amino acids in different life forms?

  1. Jul 21, 2017 #1
    Hello,

    Are the 20 amino acids that are usually referenced when building genetically coded proteins in all of life, and no other amino acids or are these only in humans and animals?

    I found the sentence below on this website and I wasn't sure what to make of it, is it true that there are hundreds of amino acids in life, depending on the species? This made me wonder about the variety of nucleobases in DNA in different species too.

    "Only about 20 amino acids are common in humans and animals, with 2 additional ones present in a few animal species. There are over 100 lesser known amino acids found in other living organisms, particularly plants."
    http://www.scienceclarified.com/Al-As/Amino-Acid.html

    Any thoughts really appreciated!
     
  2. jcsd
  3. Jul 21, 2017 #2

    Ygggdrasil

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    Science Advisor

    An amino acid is a general term for any organic substance containing both an amine functional group (R-NH3) and a carboxylic acid functional group (R-COOH). There are various amino acids that one would encounter in metabolism (e.g. γ-aminobutryic acid, the neurotransmitter better known as GABA). An important distinction is between proteinogenic amino acids (amino acids that get incorporated into proteins by the ribosome) and non-proteinogenic amino acids like GABA. Throughout all known organisms, there are 20 universally-used proteinogenic amino acids plus two more (selenocysteine and pyrrolysine) that are used in a few species. The fact that all known organisms use essentially the same set of proteinogenic amino acids encoded by essentially the same genetic code is one of the lines of evidence that all known life evolved from a common ancestor.
     
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