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Unformatted text preview: 438 Chapter 13 The Dynamic Genome: Transposable Elements terminal inverted repeats and encodes a single protein, the transposase. The nonautonomous Ds element does not encode transposase and thus cannot transpose on its own. When Ac is in the genome, its transposase can bind to both ends of Ac or Ds elements and promote their transposition (Figure 13-21). As noted earlier in the chapter, Ac and Ds are mem- bers of a single transposon family, and there are other transposable-element families in maize. Each family con- tains an autonomous element encoding a transposase that can move elements in the same family but cannot move elements in other families, because the transposase can bind only to the ends of family members. Although some organisms such as yeast have no DNA transposons, elements structurally similar to the P and Ac elements have been isolated from many plant and animal species. In fact, the pigment gene responsible for the snapdragon floral mutant pictured in Figure 13-6...
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- Spring '08