When a jumping gene "jumps" to different positions within the corn kernel, a color gene is "turned on" or "turned off" depending on whether it lands in a position next to a pigment gene or not. Barbara McClintock's discovery of these jumping genes in corn earned her the Nobel Prize.
Barbara McClintock. Barbara McClintock (1902-1992) was awarded a Lasker Prize in 1981 and Nobel Prize in 1983. She discovered that genes could move within and between chromosomes. Photos from: "Ten Historic Female Scientists You Should Know"