To understand the regulation of genes, the following sequence of events must be appreciated: A gene, made of DNA, is "transcribed" to produce a messenger RNA, or mRNA, that is "translated" to produce a protein product. Gene regulation refers to the regulation of production of mRNA from the gene.

Although every organism contains a collection of genes necessary for its survival and reproduction, not every gene is turned on or is producing mRNA at any given moment. At any moment or stage of development such as in the adult, only a subpopulation of genes is expressed (i.e., producing mRNA). During the development and growth of an organism, certain gene products guide and program growth. Because only a subgroup of the genome is expressed at any stage of the life cycle, gene regulation must occur. Gene regulation also occurs during a life cycle as...