[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).
Cytosine, thymine, and uracil are examples for pyrimidine bases. Adenine and guanine are the two purine bases. DNA has adenine, Guanine, cytosine, and thymine bases, whereas RNA has A, G, C, and uracil (instead of thymine). In DNA and RNA, complimentary bases form hydrogen bonds between them.That is adenine: thiamine/ uracil and guanine: cytosine are complimentary to each other. Pyrimidine has one ring and purine has two rings. â¢ Purine has a pyrimidine ring and an imidazole ring. â¢ Adenine and guanine are the purine derivative present in nucleic acids whereas cytosine, uracil and thymine are the pyrimidine derivatives present in the nucleic acids.