[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).
The purines are made up of two-carbon nitrogen ring bases with four nitrogen atoms while the pyrimidines are made up of one-carbon nitrogen ring bases with two nitrogen atoms. These two compounds serve as building blocks for a wide variety of organic compounds that can be found in nature and in our bodies.n microbiology, there are two types of nitrogenous bases that make up the two different kinds of nucleotide bases in DNA and RNA. These two types are called purines and pyrimidines.