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Ribozymes and deoxyribozymes are two types of nucleic acid enzymes that can catalyze specific chemical reactions. Ribozymes are composed of RNA, while deoxyribozymes are composed of DNA. Some ribozymes are found in nature and play important roles in biological processes, such as RNA splicing and translation. Deoxyribozymes, on the other hand, are mostly artificial and have been discovered by in vitro selection from random sequences. Both ribozymes and deoxyribozymes have potential applications in biotechnology, such as biosensors and gene regulation. However, deoxyribozymes have some advantages over ribozymes, such as higher stability and easier binding to metal cofactors.
Transposons, mobile DNA, or jumping genes are chromosomal segments that can undergo transposition (translocation) in the genome. They are a class of genetic elements that can “jump” to different locations within a genome. Although these elements are frequently called “jumping genes,” they are always maintained in an integrated site in the genome. In addition, most transposons eventually become inactive and no longer move.
Transposons were first discovered in corn (maize) during the 1940s and 50s by American scientist Barbara McClintock, whose work won her the Nobel Prize for Physiology or Medicine in 1983.
Most, if not all, of these elements encode an enzyme called transposase, which acts to cleave the ends of the transposon, freeing it from its initial location in the genome. Transposase also cleaves target sites where the element is to be inserted.
Retrotransposons represent a highly unique group of transposable elements and form large portions of the genomes of many eukaryotes. Retrotransposons function by a “copy and paste” mechanism. Thus, they leave behind the original copy and generate a second copy that is inserted elsewhere in the genome. This process results in the insertion of repetitive sequences of DNA throughout the genome. The transposable DNA is copied into RNA. The RNA segment then jumps to another location in the genome. The RNA is copied back into DNA by reverse transcriptase. There are several different types of retrotransposons, including long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs). About 20 percent of the human genome is made up of LINEs.
Transposon | genetics | Britannica