The following is an edited excerpt.
In the 1940s, geneticist Barbara McClintock of the Cold Spring Harbor Laboratory in New York wanted to know: Why is it that some corn kernels show an uneven splattering of color? If the DNA in every cell in each kernel contains the same pigment gene (or genes), then why isn’t that color expressed the same way in every cell?
As McClintock would discover (and, three decades later, win a Nobel Prize for), the color variation in maize comes from transposons, or so-called jumping genes. These stretches of DNA hop out of their original spot in the genome and then wedge themselves in another, random place. When they land, they may disrupt the activities of nearby genes, including pigment genes. The jumping patterns are different in every cell, thus explaining the color variability.
Ever since McClintock’s big discovery, two ideas have dominated the scientific literature on jumping genes…
Read the full article here: The Jumping Gene: Friend or Foe?