rrna definition
Ribosomal RNA: A molecular component of a ribosome, the cell's essential protein factory. Ribosomal RNA (rRNA) fabricates polypeptides (assemblies of amino acids that make up proteins).lthough the ribosome consists of both ribosomal RNA (rRNA) and protein, the active site on the large unit of the ribosome -- the site of the chemical reaction that changes genetic information into the beginnings of a protein -- contains only rRNA.