[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).
This lesson will describe the definition and structure of thymine as it relates to the formation of DNA. Also, there will be a small discussion about key facts that separate thymine from the other bases used to form the DNA helix.ach respective base is in the shape of a ring-like form and there are two types. A purine is a base that contains a double ring form. By contrast, a pyrimidine is a base that contains a single ring form. Adenine and guanine are the purines. Thymine and cytosine are the pyrimidines.