Final answer:
American geneticist Barbara McClintock discovered transposons, or jumping genes, in the 1940s through her work on maize genetics and was awarded the Nobel Prize in 1983 for her findings.
Step-by-step explanation:
The transposable elements, or jumping genes, known as transposons, were discovered by American geneticist Barbara McClintock through her pioneering work on maize genetics in the 1940s. McClintock's astute observations of the unexpected behavior of certain genes in maize led her to identify the first transposon, for which she was later awarded the 1983 Nobel Prize in Physiology or Medicine.
Transposons are composed of DNA that includes inverted repeat sequences and a gene for the enzyme transposase, allowing them to excise and integrate into different locations within the genome, influencing gene and protein expression, and introducing genetic diversity.