Gene expression is the process by which the information in a gene is used to synthesize a functional product — most often a protein, but for non-protein-coding genes an RNA species such as ribosomal RNA, transfer RNA, or small nuclear RNA. Determining what a given gene does proceeds from the gene toward its phenotype by two complementary strategies: gene knockout, in which the candidate gene is disabled and the resulting loss (or persistence) of a phenotype is taken as evidence for (or against) that gene's role in the function, and reverse genetics by sequence homology, in which a sequenced gene of unknown function is matched against homologous sequences whose products are already characterized, and function is inferred by similarity. The concept belongs to molecular genetics and functional genomics within molecular biology, and it supplies the experimental logic that connects genotype to phenotype.
Gene expression is the process by which the information in a gene is used to synthesize a functional product — most often a protein, but for non-protein-coding genes an RNA species such as ribosomal …