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Modern Genetic Analysis Chapter 13. Transposable Genetic Elements
Rearrangements Mediated by Transposable Elements

Transposable elements generate a high incidence of deletions in their vicinity. These deletions emanate from one end of the element into the surrounding DNA (Figure 13-14 on the next page). Such events, as well as element-induced inversions, can be viewed as aberrant transposition events. Transposons also give rise to readily detectable deletions in which part of the element is deleted together with varying lengths of the surrounding DNA. This process of imprecise excision is now recognized as deletions or inversions emanating from the internal ends of the IR segments of the transposon. The process of precise excisionthe loss of the transposable element and the restoration of the gene that was disrupted by the insertionalso occurs, although at very low rates compared with the frequencies of the events just described.

MESSAGE
Some DNA sequences in bacteria and phages act as mobile genetic elements. They are capable of joining different pieces of DNA and thus are capable of splicing DNA fragments into or out of the middle of a DNA molecule. Some naturally occurring mobile or transposable elements carry antibiotic-resistance genes.

© 1999 by W. H. Freeman and Company. All rights reserved.