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the RNA of ribosomes and polyribosomes.
n. Abbr. rRNA
The RNA that is a permanent structural part of a ribosome.
ribosomal RNA Molecular biology Any of a family of single-stranded nucleic acids ranging from 100 to 3000 bases in length, that assemble in heteromultimeric complexes with proteins, to form ribosomes, the 'docking stations' for mRNA and nascent polypeptide strands. See Ribosome, RNA. Cf mRNA, tRNA.
ribosomal RNA (rRNA) Ribonucleic acid that is a permanent structural feature of RIBOSOMES.
ribosomal RNA (rRNA) a form of RNA transcribed from DNA in the NUCLEOLI of EUKARYOTE cells or clustered ribosomal genes in PROKARYOTES, that complexes with various proteins (r proteins) to form the RIBOSOME. rRNA constitutes the major proportion of RNA in cells and occurs in a number of different types (for example, in bacterial ribosomes: 23S rRNA, 16S rRNA and 5S rRNA). In protein synthesis a sequence near the 3′-end of the 16S rRNA interacts with the SHINE-DALGARNO sequence to initiate TRANSLATION. Certain regions of rRNA have been highly conserved during evolution and comparative sequencing studies of rRNAs are used to determine evolutionary relationships between organisms and to construct PHYLOGENETIC TREES.