CRISPR-Cas9 Mechanism

graph TD Target[Target DNA] --> Complex[CRISPR-Cas9 complex] sgRNA[sgRNA] --> Complex Cas9[Cas9 nuclease] --> Complex Complex --> PAM[PAM recognition] PAM --> Bind[Target binding] Bind --> Cleave[Double-strand break] Cleave --> DSB[DSB 3 bp upstream of PAM] DSB --> Repair{Repair Pathway?} Repair -->|NHEJ| NHEJ[Non-Homologous End Joining] Repair -->|HDR| HDR[Homology-Directed Repair] NHEJ --> Edit[Gene knockout] HDR --> Edit2[Precise edit] style Target fill:#ff6b6b,color:#fff style sgRNA fill:#ff6b6b,color:#fff style Cas9 fill:#ffd43b,color:#000 style Complex fill:#ffd43b,color:#000 style PAM fill:#51cf66,color:#fff style Bind fill:#51cf66,color:#fff style Cleave fill:#51cf66,color:#fff style DSB fill:#74c0fc,color:#fff style Repair fill:#b4b4dc,color:#000 style NHEJ fill:#51cf66,color:#fff style HDR fill:#51cf66,color:#fff style Edit fill:#b197fc,color:#fff style Edit2 fill:#b197fc,color:#fff