[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 DNA nucleotide is one of two kinds of bases... a pyrimidine or a purine. The purine is a heterocyclic (two-ring) molecule with a 5 member and 6 member ring each containing 2 â¦ Nitrogens.Purines are just a single ring with 2 Nitrogens.Each base is paired with a sugar (ribose) less one oxygen (hence the prefix de-oxyribose).here are four nucleotides that make up DNA: Adenine, Thymine, Guanine and Cytosine. There are billions of them that make up one strand of DNA. Adenine always pairs with Thymi â¦ ne and Guanine always pairs with Cytosine.