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Unformatted text preview: 432 Chapter 13 The Dynamic Genome: Transposable Elements Tn10 I S 1 I S 1 t e t R IS 2 Tn5 Tn4 IS 1 c m R kan R IS50 IS50 sm R su R am p R Tn3 h g R IS 1 Resistance-determinant segment Figure 13-10 A schematic map of a plasmid carrying simple and composite transposon-resistance genes. Genes encoding resistance to the antibiotics ( tet R ), kanamycin ( kan R ), streptomycin ( sm R ), sulfonamide ( su R ), and ampicillin ( amp R ) and to mercury ( Hg R ) are shown. The resistant-determinant segment can move as a cluster of resistance genes. Tn3 is within Tn4. Each transposon can be transferred independently. [Simplified from S. N. Cohen and J. A. Shapiro, Transposable Genetic Elements. Copyright 1980 by Scientific American, Inc. All rights reserved.] complementary strand. In this example, integration generates a five-base-pair duplication, called a target- site duplication. Virtually all transposable elements (in both prokaryotes and eukaryotes) are flanked by a target-...
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- Spring '08