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.
An observable characteristic of an organism that arises from environmental factors, or a combination of environmental and genetic (genotype) factors. Organisms with the same genotype can have very different phenotypes.