Practice question

Dicer is multidomain RNase III endoribonuclease harboring N-terminal helicase, DUF283, PAZ, two RNase III domains, dsRNA-binding domain measuring distance from termini. Dicer cleaves long double-stranded RNA including viral intermediates and endogenous hairpin precursors into 21-23 nucleotide short interfering RNAs or microRNA duplexes bearing characteristic 2-nucleotide 3' overhangs, 5' monophosphate, 3' hydroxyl groups. Size determination relies on helical ruler mechanism positioning catalytic centers approximately two helical turns apart. Human Dicer partners with TRBP, fission yeast Dcr1 processes centromeric dsRNA into siRNAs essential for heterochromatin nucleation via RITS recruitment demonstrating conserved role across eukaryotes in initiating silencing pathways.