Homeobox

Homeobox: A short DNA sequence about 180 base pairs long with an almost identical base sequence in all genes that contain it. Homeoboxes determine the development of limbs and other body parts in the fetus. Homeoboxes are present in the genomes of many organisms from fruit flies to humans and appear to determine when particular groups of genes are expressed during embryonic development. A gene that contains a homeobox is called a Hox gene.