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Transposons are genetic templates that move within the genome, causing mutations or defects. They were discovered in the 1930s and have two varieties, class I and class II. Their purpose is not fully understood, but they can cause physical changes, such as in corn. Researchers hope to use them to prevent unwanted mutations and make breakthroughs in disease treatment.
Transposons, also called transposable elements (TEs) or ‘jumping genes’, are genetic templates that move from one location in the genome to another. TEs are commonly found in the deoxyribonucleic acid (DNA) sequences of living organisms, including humans and plants. Changing the position of transposons within a genetic structure can sometimes cause visible mutations or defects.
Initially, transposable elements were discovered by Barbara McClintock and Marcus Rhoades in the early 1930s. Prior to this discovery, scientists believed that DNA was stable and immutable. The study of transposons has greatly improved the understanding of how genetic factors can affect an organism. While these groundbreaking studies were not immediately accepted, McClintock’s work earned her a Nobel Prize in 1983.
There are two general varieties of transposons. Class II transposons are composed of DNA that moves from one genetic locus to another in a direct manner, similar to “copy and paste” letters from one area of a sentence to a different locus. Alternatively, class I transposons have an additional step in the duplication process, copying a DNA template onto ribonucleic acid (RNA) and then converting it back to DNA at another location. A class I transposon is sometimes called a “retrotransposon,” which means that each piece of genetic information must be decoded by the RNA before it can be inserted into a new location.
Scientists don’t fully understand the benefit or purpose of transposable elements as of early 2012. In fact, many experts call them “junk” DNA because they don’t appear to improve the quality of a host organism. Some scientists theorize that variety caused by transposable elements is important to natural selection; however, there is no evidence that this is true.
As research into the benefits continues, the physical changes caused by TEs are easy to observe. For example, genetic mutations caused by transposable elements can be observed in the “Indian” variety of corn. Each transposon creates an uncolored kernel. The dark and light mutated kernel patterns give the cob a mosaic look. These transposon gene patterns do not harm the plant, but give it a discolored appearance.
Some researchers hope to use transposable elements to change genetic structures in a positive way. By controlling each transposon, scientists may be able to prevent unwanted mutations from occurring. The ability to influence mutations at the genetic level could lead to major breakthroughs in disease treatment and prevention.
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