P elements are transposable elements found in Drosophila. They are most intriguing and useful for the geneticists.
The full size P element resembles the simple transposons of bacteria in that its ends are short, inverted repeats, and encodes a single protein called transposase that is responsible for mobilization.
They are also used to generate new mutations by random insertion and gene knockouts.
They are valuable tool to tag and then clone any number of genes. After the interrupted gene had been cloned, the fragments from the mutant gene can be used as a probe to isolate the wild-type allele.
P elements can also be manipulated and used to insert almost any DNA (deoxyribonucleic acid) into the Drosophila genome.
P element-mediated gene transfer requires inserting the DNA of interest between the inverted repeats necessary for the P element transposition. This recombinant DNA, along with helper intact P element DNA is then co-injected into very early embryos.
The progeny of these embryos are then screened for those that contain the randomly inserted DNA of interest.