The process by which information from a gene is used to synthesize a functional gene product, such as a protein.Gene expression is the process by which the information encoded in a gene is converted into a functional product, typically a protein. It involves two main steps: transcription, where the DNA sequence is copied into messenger RNA (mRNA), and translation, where the mRNA is read by ribosomes to assemble amino acids into a protein. This process is tightly regulated, allowing cells to respond to environmental signals and differentiate into specialized types.
The central dogma of molecular biology, describing the flow of information from DNA to RNA to protein, was articulated by Francis Crick in 1957. The detailed mechanisms of transcription and translation were worked out through the 1960s and 1970s.
Transcription begins when transcription factors bind to promoter regions of DNA, recruiting RNA polymerase to synthesize mRNA. The mRNA is then processed (splicing, capping, polyadenylation) and exported to the cytoplasm. During translation, ribosomes read the mRNA in triplets (codons), each specifying an amino acid, with transfer RNA (tRNA) delivering the correct amino acids. The resulting protein folds into its functional shape, often assisted by chaperones.
Gene expression analysis is used in medicine to diagnose diseases, tailor treatments (pharmacogenomics), and develop gene therapies. It is also central to biotechnology, where engineered cells produce insulin, antibodies, and other therapeutic proteins.
Only about 1-2% of the human genome codes for proteins, yet the rest is largely involved in regulating gene expression, including enhancers, silencers, and non-coding RNAs.















