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recognizes inverted repeats and target sequences recognizes inverted repeats and target sequences recognizes internal resolution site (IRS)

recognizes internal resolution site (IRS)

of itself that is liberated as a free intermediate to find a new home. Instead, complex transposons trick the host cell into duplicating their DNA during the transposition process.

Replicative transposition proceeds as follows. The transposase starts by making single stranded nicks at the ends of both the transposon and the target sequence. Next, it joins the free ends to create a cointegrate in which both DNA molecules are linked together via single strands of transposon DNA (Fig. 15.08). The presence of single-stranded DNA alerts the host cell repair systems, which synthesize the complementary strands, thus duplicating the transposon. This leaves a cointegrate of two double-stranded DNA molecules linked by two transposons. Note that each copy of the trans-poson consists of one old and one new strand of DNA.

The function of resolvase is to resolve the cointegrate and separate the two DNA molecules again. It does this by recognizing the two IRS sequences, in the middle of the two copies of the transposon, and carrying out recombination between them (Fig. 15.08). This generates two free DNA molecules each carrying a single copy of the cointegrate A temporary structure formed by linking the strands of two molecules of DNA during transposition, recombination or similar processes

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Single strand

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