Gene expression

Gene expression is how the information in a gene (the sequence of DNA base pairs) is made into a product (such as a protein or RNA). The basic idea is that DNA is transcribed into RNA, which is then translated into proteins. Proteins make many of the structures and all the enzymes in a cell or organism.

Several steps in gene expression may be tuned. This includes both the transcription and translation stages, and the final folded state of a protein. Gene regulation switches genes on and off, and so controls cell differentiation, and morphogenesis. Gene regulation may also serve as a basis for evolutionary change: control of the timing, location, and amount of gene expression can have a profound effect on the development of the organism.

The expression of a gene may vary a lot in different tissues. That is how the tissues become different from each other. This is called pleiotropism. This term is important in genetics.