Create a detailed molecular diagram of the CRISPR-Cas9 gene editing mechanism: sgRNA design with 20nt spacer and scaffold, Cas9 protein domains (REC, NUC with RuvC and HNH), PAM recognition (5'-NGG-3'), R-loop formation, double-strand break generation, and two repair pathways — NHEJ (with indel outcomes) and HDR (with donor template integration). Show DNA as double helix with base-pair resolution at the cut site.
