Practice question

Copy-and-paste mechanism characterizes Class I retrotransposons where original copy remains at donor locus while new copy inserts elsewhere, leading to gradual increase in element number. After transcription into RNA, reverse transcriptase synthesizes cDNA copy often via target-primed reverse transcription where 3' end of nicked genomic target primes reverse transcription using element RNA as template. Integrase or endonuclease ligates cDNA into genome producing target site duplication. Replicative nature explains high abundance of LINE-1 and Alu in mammalian genomes and ongoing insertional mutagenesis. This principle illustrates essential molecular mechanisms governing replication fidelity and mutation fixation relevant for exam interpretation.