Practice question

Ac element is autonomous member of maize Ac-Ds family because its 4565 bp sequence includes complete open reading frame encoding 807 amino acid transposase with DNA-binding and catalytic DDE domains capable of recognizing terminal inverted repeats and orchestrating cut-and-paste transposition. Autonomous status allows independent excision and reinsertion without external help, mobilizes non-autonomous Ds elements in trans, and mediates chromosome breakage phenotype. Regulation involves alternative splicing producing multiple isoforms and negative feedback at high transposase concentrations limiting transposition frequency in plant development. This principle illustrates essential molecular mechanisms governing replication fidelity and mutation fixation relevant for exam interpretation.