ribonucleic acid

A macromolecule consisting of ribonucleoside residues connected by phosphate from the 3′-hydroxyl of one to the 5′-hydroxyl of the next nucleoside. RNA is found in all cells, in both nuclei and cytoplasm and in particulate and nonparticulate form, and also in many viruses; polynucleotides made in vitro are generally called such. Various RNA fractions are identified by location, form, or function.
- acceptor RNA SYN: transfer RNA.
- antisense RNA the transcription product of the DNA antisense strand; it can play a role in the inhibition of translation. SEE ALSO: antisense DNA.
- chromosomal RNA RNA associated with the chromosome (not mRNA, tRNA, or rRNA) that may have a role in transcription.
- heterogeneous nuclear RNA (hnRNA) an ill-defined form of RNA, of high molecular weight, that never leaves the nucleus and is thought to be the precursor of messenger RNA.
- informational RNA SYN: messenger RNA.
- initiation tRNA tRNA in prokaryotes containing a formyl-methionyl residue that initiates translation. SYN: formyl-methionyl-tRNA, starter tRNA.
- messenger RNA (mRNA) the RNA reflecting the exact nucleoside sequence of the genetically active DNA and carrying the “message” of the latter, coded in its sequence, to the cytoplasmic areas where protein is made in amino acid sequences specified by the mRNA, and hence primarily by the DNA; viral RNAs are considered to be natural messenger RNA s. SYN: informational RNA, template RNA.
- messengerlike RNA (mlRNA) heterogeneous nuclear RNA.
- nuclear RNA (nRNA) rNA found in nuclei, or associated with DNA, or with nuclear structures (nucleoli).
- ribosomal RNA the RNA of ribosomes and polyribosomes.
- small nuclear RNA (snRNA) small RNA ( i.e., about 90–300 nucleotides long) in the nucleus believed to have a role in RNA processing and cellular architecture.
- soluble RNA (sRNA) SYN: transfer RNA. [soluble in molar salt]
- starter tRNA SYN: initiation tRNA.
- suppressor tRNA the tRNA associated with a suppressor mutation.
- template RNA SYN: messenger RNA.
- transfer RNA (tRNA) short-chain RNA molecules present in cells in at least 20 varieties, each variety capable of combining with a specific amino acid (see aminoacyl-tRNA). By joining (through their anticodons) with particular spots (codons) along the messenger RNA molecule and carrying their amino acyl residues along, they lead to the formation of protein molecules with a specific amino acid arrangement—the one ultimately dictated by a segment of DNA in the chromosomes. Each tRNA has about 80 nucleotides (MW about 25,000); most of the 20 varieties occur in multiple “isoacceptor” forms, separable by chromatography. Further subvarieties exist in, e.g., different strains of an organism, in subcellular organelles, and in different metabolic states. Cognate tRNAs are the tRNAs recognized by the specific amino acyl-tRNA synthetases. SYN: acceptor RNA, soluble RNA.

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ri·bo·nu·cle·ic acid .rī-bō-n(y)u̇-.klē-ik-, -.klā- n RNA

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(RNA) ri·bo·nu·cle·ic ac·id (RNA) (ri″bo-noo-kleґik) the nucleic acid in which the sugar is ribose, constituting the genetic material in the RNA viruses and playing a role in the flow of genetic information in all cells. Ribosyl moieties are linked via phosphate groups attached to their 5′ and 3′ hydroxyl groups to form the backbone of a linear polymer, with purine and pyrimidine bases attached to the sugars as side chains. The characteristic bases adenine (A), uracil (U), cytosine (C), and guanine (G) are specified by the presence of thymine (T), A, G, and C, respectively, in the gene being transcribed. Many RNA molecules contain bases modified by posttranscriptional processing (methylation, deamination, isomerization), and although mainly single-stranded, some contain regions of secondary structure such as base pairing between self-complementary sequences, which stabilizes specific conformations. In most viruses with an RNA genome, the RNA is single-stranded, but several families have a double-stranded RNA genome. For specific types of RNA, see under RNA.

Medical dictionary. 2011.

Look at other dictionaries:

  • ribonucleic acid — [rī΄bō no͞o klē′ik, rī΄bōnyo͞oklē′ik] n. [< RIBO(SE) + NUCLEIC ACID] RNA …   English World dictionary

  • ribonucleic acid — ribonucleic acid. См. РНК. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • ribonucleic acid — RNA. One of the two types of nucleic acids found in all cells. In the cell, ribonucleic acid is made from DNA (the other type of nucleic acid), and proteins are made from ribonucleic acid. Also called RNA …   English dictionary of cancer terms

  • ribonucleic acid — ribonukleorūgštis statusas T sritis chemija apibrėžtis Iš ribonukleotidų susidedanti rūgštis. santrumpa( os) RNR atitikmenys: angl. ribonucleic acid rus. рибонуклеиновая кислота ryšiai: sinonimas – ribonukleino rūgštis …   Chemijos terminų aiškinamasis žodynas

  • ribonucleic acid — ribonukleorūgštis statusas T sritis augalininkystė apibrėžtis Paprastai viengrandis iš ribonukleotidų susidedantis polinukleotidas. atitikmenys: angl. ribonucleic acid; RNA rus. рибонуклеиновая кислота; РНК ryšiai: sinonimas – RNR …   Žemės ūkio augalų selekcijos ir sėklininkystės terminų žodynas

  • ribonucleic acid — [ˌrʌɪbə(ʊ)nju: kleɪɪk, kli:ɪk] noun see RNA. Origin 1930s: ribonucleic from ribose + nucleic acid …   English new terms dictionary

  • ribonucleic acid — /ruy boh nooh klee ik, klay , nyooh , ruy /, Biochem. See RNA. Also, ribose nucleic acid. [1930 35; RIBO(SE) + NUCLEIC ACID] * * * …   Universalium

  • ribonucleic acid — n. a nucleic acid yielding ribose on hydrolysis, present in living cells, esp. in ribosomes where it is involved in protein synthesis. Usage: Abbr.: RNA. Etymology: RIBOSE + NUCLEIC ACID …   Useful english dictionary

  • ribonucleic acid — noun A derivative of DNA having ribose in place of deoxyribose, and uracil in place of thymine; its primary function is in the transcription of genetic material and subsequent …   Wiktionary

  • ribonucleic acid — (RNA)    Single stranded nucleic acid molecules composed of the ribonucleosides adenosine, guanosine, cytidine, and uridine. The three types of RNA include mRNA, rRNA, and tRNA …   Forensic science glossary

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