She received the Nobel Prize in 1983. Two broad classes of transposable elements can be identified. One class moves via a DNA intermediate b. The second class moves via an RNA intermediate. These retrotransposons require reverse transcriptase to synthesize a DNA copy of the RNA intermediate.
Most transposons cause a target site duplication as a result of their mechanism of insertion.
This duplication is left behind as footprint, or scar, if the transposon is excised. Transposon activity can cause exon shuffling.