Practice question

Terminal inverted repeats TIRs are defining structural feature of DNA transposons consisting of short sequences at opposite ends that are reverse complements, typically 10-40 bp, sometimes containing subterminal transposase binding motifs. Inverted orientation allows single transposase dimer to simultaneously contact both ends bending DNA into paired-end complex aligning catalytic DDE residues for cleavage. Sequence conservation within repeats ensures specificity, while small asymmetries differentiate autonomous and non-autonomous families. Mutagenesis of repeats abolishes binding demonstrating essential cis role for mobilization. This principle illustrates essential molecular mechanisms governing replication fidelity and mutation fixation relevant for exam interpretation.