#purine.base  any of several bases that are derivatives of purine
  supertype:  base__alkali  any of various water-soluble compounds capable of turning litmus blue and reacting with an acid to form a salt and water; "bases include oxides and hydroxides of metals and ammonia"
  subtype:  adenine  (biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA
  subtype:  guanine  a purine base found in DNA and RNA; pairs with cytosine

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