Practice question

Zinc finger nucleases link three to six fingers each contacting three base pairs, giving triplet recognition with context dependent cross-talk limiting true single base resolution. CRISPR relies on RNA-DNA pairing with mismatch tolerance. TALENs use central domain of 33-35 amino acid repeats where residues 12 and 13 called repeat variable di-residues dictate single nucleotide specificity: NI binds A, HD binds C, NG binds T, NN binds G. Each repeat recognizes exactly one base pair independently, providing genuine single base pair resolution through protein-DNA interaction ideal for precise targeting without context dependence.