Derives from the Ancient Greek words of βίος romanized

Gene expression

The extended central dogma of molecular biology includes all the processes involved in the flow of genetic information.

Main article: Gene expression
Gene expression is the molecular process by which a genotype gives rise to a phenotype, i.e., observable trait. The genetic information stored in DNA represents the genotype, whereas the phenotype results from the synthesis of proteins that control an organism's structure and development, or that act as enzymes catalyzing specific metabolic pathways. This process is summarized by the central dogma of molecular biology, which was formulated by Francis Crick in 1958.^[83][84][85] According to the Central Dogma, genetic information flows from DNA to RNA to protein. Hence, there are two gene expression processes: transcription (DNA to RNA) and translation (RNA to protein).^[86] These processes are used by all life—eukaryotes (including multicellular organisms), prokaryotes (bacteria and archaea), and are exploited by viruses—to generate the macromolecular machinery for life.
During transcription, messenger RNA (mRNA) strands are created using DNA strands as a template, which is initiated when RNA polymerase binds to a DNA sequence called a promoter, which instructs the RNA to begin transcription of one of the two DNA strands.^[87] The DNA bases are exchanged for their corresponding bases except in the case of thymine (T), for which RNA substitutes uracil (U).^[88] In eukaryotes, a large part of DNA (e.g., >98% in humans) contain non-coding called introns, which do not serve as patterns for protein sequences. The coding regions or exons are interspersed along with the introns in the primary transcript (or pre-mRNA).^[87] Before translation, the pre-mRNA undergoes further processing whereby the introns are removed (or spliced out), leaving only the spliced exons in the mature mRNA strand.^[87]
The translation of mRNA to protein occurs in ribosomes, whereby the transcribed mRNA strand specifies the sequence of amino acids within proteins using the genetic code. Gene products are often proteins, but in non-protein-coding genes such as transfer RNA (tRNA) and small nuclear RNA (snRNA), the product is a functional non-coding RNA.^[89][90]