ribosome(redirected from E (exit) site)
Also found in: Dictionary, Thesaurus, Encyclopedia.
any of the intracellular ribonucleoprotein organelles concerned with protein synthesis, found either bound to cell membranes or free in the cytoplasm. They may occur singly or in clusters (polyribosomes). The genetic code is translated when ribosomes attach to messenger RNA.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
A granule of ribonucleoprotein, 120-200 Ǻ in diameter, that is the site of protein synthesis from aminoacyl-tRNAs as directed by mRNAs.
Synonym(s): Palade granule
Farlex Partner Medical Dictionary © Farlex 2012
A structure composed of RNA and protein, present in large numbers in the cytoplasm of living cells and serving as the site for assembly of polypeptides encoded by messenger RNA.
ri′bo·so′mal (-sō′məl) adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
A granule of ribonucleoprotein, 120-150 Å in diameter, which is the site of protein synthesis from aminoacyl-tRNAs as directed by mRNAs.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
ribosomeA spherical cell ORGANELLE made of RNA and protein which is the site of protein synthesis in the cell by linking amino acids into chains. Ribosomes may be free or may be attached to the endoplasmic reticulum. During translation, ribosomes attach to MESSENGER RNA molecules and travel along them, synthesizing polypeptides as they go.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
ribosomea small particle (not an ORGANELLE) found in the cytoplasm of all cells, composed of protein and RIBOSOMAL RNA. Each ribosome is composed of two subunits of different sizes which sediment at different rates during centrifugation (see ULTRACENTRIFUGE). PROKARYOTES have ribosome with 70 S size and mass; EUKARYOTES have larger ribosomes with 80 S size and mass. Ribosomes bind to the 5′ end of MESSENGER RNA (see POLYNUCLEOTIDE CHAIN) and travel towards the 3′ end, with TRANSLATION and POLYPEPTIDE synthesis occurring as they go along. Frequently several ribosomes are attached to one piece of mRNA, forming a POLYRIBOSOME.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
Palade,George Emil, Romanian-U.S. cell biologist and Nobel laureate, 1912–.
Palade granule - a granule of ribonucleoprotein, the site of protein synthesis from aminoacyl-tRNAs as directed by mRNAs. Synonym(s): ribosome
Weibel-Palade bodies - see under Weibel
Medical Eponyms © Farlex 2012