Evolution of Genes

Over time, some gene copies mutate to lose their function entirely. Such so-called pseudogenes may arise through accumulation of mutations that A gene family is descended from a common ancestral gene. prevent translation of the gene, such as an insertion or deletion that stops translation at the beginning of the gene sequence. Pseudogenes also arise from mutation in a gene's promoter region. The promoter is the site at the beginning of the gene that attracts the enzyme called RNA polymerase. Without a functional promoter, the gene cannot be transcribed effectively, and so cannot lead to protein production.

Retroposition is a very common source of pseudogenes. Pseudogenes have been discovered because their sequences are similar to functional genes. In humans, pseudogenes are known to exist for topoisomerase (a gene that cuts DNA to prevent twisting), ferritin (an iron storage protein), two different forms of actin, and many other genes.