ribosome


ribosome
ribosomal, adj.
/ruy"beuh sohm'/, n. Cell Biol.
a tiny, somewhat mitten-shaped organelle occurring in great numbers in the cell cytoplasm either freely, in small clusters, or attached to the outer surfaces of endoplasmic reticula, and functioning as the site of protein manufacture. See diag. under cell.
[1955-60; RIBO(SE) + -SOME3]

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Tiny particle, the site of protein synthesis, that is present in large numbers in living cells.

They occur both as free particles within cells and, in eukaryotes, as particles attached to the membranes of the endoplasmic reticulum. They are 40% protein and 60% RNA. Ribosomes account for a large proportion of the total RNA of a cell. Proteins newly formed on ribosomes detach and migrate to other parts of the cell to be used.

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 tiny particle that is present in large numbers in all living cells and serves as the site of protein synthesis. Ribosomes occur both as free particles in prokaryotic and eukaryotic cells and as particles attached to the membranes of the endoplasmic reticulum in eukaryotic cells. Ribosomes can vary in size, although an average ribosome measures about 200 angstroms in diameter and consists of about 40 percent protein and 60 percent RNA. Ribosomes are usually made up of three or four RNA molecules and anywhere from 40 to 80 different proteins. In shape the ribosome is composed of two subunits, a larger one and a smaller one, each of which has a characteristic shape. Ribosomes are very numerous in a cell and account for a large proportion of its total RNA.

      Ribosomes are the sites at which information carried in the genetic code is converted into protein molecules. Ribosomal molecules of messenger RNA (mRNA) determine the order of transfer RNA (tRNA) molecules that are bound to triplets of amino acids (codons). The order of tRNA molecules ultimately determines the amino acid sequence of a protein because molecules of tRNA catalyze the formation of peptide bonds between the amino acids, linking them together to form proteins. The newly formed proteins detach themselves from the ribosome site and migrate to other parts of the cell for use.

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Universalium. 2010.

Look at other dictionaries:

  • ribosome — [ ribozom ] n. m. • v. 1960; de ribo et some ♦ Biol. Organite cytoplasmique formé de trois types différents d acides ribonucléiques, associés à cinquante deux protéines distinctes et déchiffrant le code inscrit dans l A. R. N. messager. ⇒… …   Encyclopédie Universelle

  • ribosome — ribosome. См. тельце Паладе. (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.

  • ribosome — 1958, coined by U.S. microbiologist Richard B. Roberts (1910 1980) from ribo(nucleic acid) + some body …   Etymology dictionary

  • ribosome — [rī′bə sōm΄] n. [< RIBOSE + SOME3] a minute, spherical particle composed of RNA and proteins and present in great numbers in the cytoplasm of cells: proteins are manufactured at the ribosomal surface following genetic instructions carried… …   English World dictionary

  • Ribosome — cell, showing subcellular components including ribosomes (3). Organelles: (1) nucleolus (2) nucleus (3) ribosomes (little dots) (4) vesicle (5) rough endoplasmic reticulum (ER) (6) Golgi apparatus (7) Cytoskeleton (8) smooth ER (9) mitochondria… …   Wikipedia

  • Ribosome — Schema d une cellule animale type : (1) nucleole (2) Noyau (3) ribosomes (petits points) (4) vesicule (5) Réticulum endoplasmique granuleux (REG) (6) Appareil de Golgi (7) cytosquelette (8) Réticulum endoplasmique lisse (9) Mitochon …   Wikipédia en Français

  • Ribosome — The cell s essential protein factory. A tiny particulate structure located in the cytoplasm of the cell (outside the nucleus), the ribosome is composed of two subunits, one larger than the other. Both subunits were believed to contain both RNA… …   Medical dictionary

  • ribosome — ribosoma statusas T sritis augalininkystė apibrėžtis Ląstelių organoidas, kuriame vyksta baltymų biosintezė. atitikmenys: angl. ribosome rus. рибосома …   Žemės ūkio augalų selekcijos ir sėklininkystės terminų žodynas

  • ribosome — noun Date: 1958 any of the RNA rich cytoplasmic granules that are sites of protein synthesis see cell illustration • ribosomal adjective …   New Collegiate Dictionary

  • ribosome — n. [L. alteration of arabinose; Gr. soma, body] Aggregations of RNA and proteins that act in synthesis of proteins …   Dictionary of invertebrate zoology


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