RNA is a nucleic acid which is made up of a ribose sugar, nitrogenous bases (adenine, uracil, guanine and thymine) and phosphate group. Transcription of DNA strand results in the formation of mRNA. Messenger RNA or mRNA has the coding sequence which is required to produce the protein through the process of translation. Double-stranded RNA occurs in some viruses such as reovirus, wound tumour virus, etc. The tRNA or transfer RNA is an adapter molecule which is meant for transferring amino acids to ribosomes for the synthesis of polypeptides. They have special sites onto which the amino acids can bind and are taken to the site of protein synthesis. rRNA or ribosomal RNA is the most abundant RNA found in a cell. The rRNA is a constituent of ribosomes.