Ribonucleic acid. Linear, generally single-stranded polymer, composed of ribose nucleotides, that is synthesized by transcription of DNA or by copying of RNA. The three types of cellular RNA – mRNA, rRNA, and tRNA – play different roles in protein synthesis.
Physical and functional unit of heredity which carries information from one generation to the next. In molecular terms, it is the entire DNA sequence – including exons, introns, and noncoding transcription-control regions – necessary for production of a functional protein or RNA.