nucleoside
enUKnu·cle·o·side
N0187800 (no͞o′klē-ə-sīd′, nyo͞o′-)nucleoside
(ˈnjuːklɪəˌsaɪd)nu•cle•o•side
(ˈnu kli əˌsaɪd, ˈnyu-)n.
Noun | 1. | nucleoside - a glycoside formed by partial hydrolysis of a nucleic acid |
单词 | nucleoside | |||
释义 | nucleosideenUKnu·cle·o·sideN0187800 (no͞o′klē-ə-sīd′, nyo͞o′-)nucleoside(ˈnjuːklɪəˌsaɪd)nu•cle•o•side(ˈnu kli əˌsaɪd, ˈnyu-)n.
NucleosideenUKnucleoside[′nü·klē·ə‚sīd]Nucleosidea compound that consists of a nitrogenous base and a carbohydrate. A nucleoside whose carbohydrate portion is ribose is called a ribonucleoside, and a deoxyribose-containing nucleoside is called a deoxyribonucleoside. Nucleosides have the following structural formula: In deoxyribonucleosides, X is replaced by a hydrogen atom, while in ribonucleosides, a hydroxyl group replaces X. R can be any purine or pyrimidine base. A nucleoside can be regarded as the product of the dephos-phorylation of a nucleotide. In a nucleoside, the purine or pyrimidine base is connected to the 1′ carbon atom by a β-glycoside bond. Nucleosides are named according to their base; thus, adenosine contains adenine, guanosine—guanine, uridine—uracil, cytidine—cytosine, and thymidine—thymine. The nucleosides that contain hypoxanthine and xanthine are called inosine and xanthosine, respectively. A few other nucleosides exist, which are structurally similar to those mentioned but which differ in the particular base, carbohydrate component, or type of internal bonds. Free nucleosides are present in small quantities in several biological substances. The significance of most nucleosides, however, is their occurrence as constituents of nucleotides and nucleic acids. I. B. ZBARSKH nucleosideenUKnucleoside[noo´kle-o-sīd]nu·cle·o·side (Nuc, N),(nū'klē-ō-sīd'),nucleoside(no͞o′klē-ə-sīd′, nyo͞o′-)nu·cle·o·side(nū'klē-ō-sīd)nucleosideA molecule compounded of a purine or pyrimidine base attached to a sugar (ribose or deoxyribose). The genetic code in DNA and RNA depends on the order of the nucleosides. A nucleoside is a NUCLEOTIDE without the phosphate group.nucleosidea chemical compound in which a nitrogenous base is attached to a sugar. Such a structure occurs in DNA nucleotides where a phosphate group is attached to the deoxyribose sugar of the nucleoside.nu·cle·o·side(nū'klē-ō-sīd)nucleosideenUK
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