<cell biology> A small particulate organelle found in prokaryotes and eukaryotes and also within mitochondria and chloroplasts, but differing in size and composition. Made of two subunits, each being an RNA protein complex. Ribosomes are responsible for the translation of mRNA which may occur in the cytoplasm (see polyribosomes) or on rough endoplasmic reticulum.

Origin: Gr. Soma = body

(11 Mar 2008)