[too rz duh fawrs, -fohrs; French toor duh fawrs] /ËtÊÉrz dÉ ËfÉrs, -ËfoÊrs; French tur dÉ ËfÉrs/ (Show IPA) 1. an exceptional achievement by an artist, author, or the like, that is unlikely to be equaled by that person or anyone else; stroke of genius: Herman Melville's Moby Dick was a tour de force. 2. a particularly adroit maneuver or technique in handling a difficult situation:
edit Nucleobases. Purines make up two of the four nucleobases in DNA and RNA: adenine and guanine. Pyramidines make up the other bases in DNA and RNA: cytosine, thymine (in DNA) and uracil (in RNA).
A pyrimidine is a single ringed base. The three kinds are; Cytosine, Thymine (in Dna) and Uracil (only in Rna). A purine is a double ringed base. the two kinds are; Adenine and Guanine. Adenine pairs with Thymine in Dna-or Uracil in Rna; Guanine pairs with Cytosine in both Dna and Rna.yrimidines are just the 6 member ring you made in the purine. It is called a 1 3 diazine ring. Pyrimidines are the basis of the other nucleic bases in DNA and RNA called cytosine, uracil, and thymine. Pyrimidines have much lower boiling points and molecular masses than purines.