By observing and experimenting with variations in the coloration of kernels of corn (maize), McClintock discovered that genetic information is not stationary. By tracing pigmentation changes in maize and using a microscope to examine that plant's large chromosomes, she isolated two genes that she called "controlling elements." These genes controlled the genes that were actually responsible for pigmentation. McClintock found that the controlling elements could move along the chromosome to a different site, and that these changes affected the behaviour of neighbouring genes. She suggested that these transposable elements were responsible for new mutations in pigmentation or other characteristics. The importance of her research was not recognized until the 1960s, when Francois Jacob and Jacques Monod discovered controlling elements in bacteria similar to those McClintock found in corn. McClintock won belated acclaim for her research, which significantly increased the knowledge of genetic function and organization.
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