Practice question

Long terminal repeat retrotransposons possess structure reminiscent of integrated retroviruses, flanked by two direct repeats in same orientation termed LTRs, each 300-500 bp containing U3-R-U5 subdivisions with promoter and polyadenylation signals. During reverse transcription, two LTRs become identical copies surrounding internal gag-pol coding region. Dual LTRs facilitate transcription, template switching during reverse transcription, and provide integrase att attachment sites. Integration generates short target site duplication flanking element, distinguishing LTR elements from non-LTR retrotransposons lacking terminal repeats. This principle illustrates essential molecular mechanisms governing replication fidelity and mutation fixation relevant for exam interpretation.