Practice question

Retrotransposons are grouped as Class I elements because they transpose through RNA intermediate that is reverse transcribed into complementary DNA for integration. Internal promoters drive transcription of element RNA, translated to produce reverse transcriptase and other proteins. cDNA synthesis and insertion constitute copy-and-paste process increasing copy number per event. Distinction from Class II DNA transposons emphasizes requirement for reverse transcriptase, polyadenylation signals, and RNA handling, aligning retrotransposons with retroviral life cycle lacking extracellular virion formation but sharing integrase based insertion. This principle illustrates essential molecular mechanisms governing replication fidelity and mutation fixation relevant for exam interpretation.