预览提示词
A clean, publication-quality four-panel mechanism figure laid out left-to-right as a horizontal sequence with numbered stages and connecting arrows, showing CRISPR-Cas9 genome editing. Panel 1, "sgRNA Design," depicts a single-guide RNA with a 20-nucleotide spacer base-pairing to the target genomic sequence and a labeled PAM site (5'-NGG-3') immediately downstream. Panel 2, "Cas9 RNP Assembly," shows the Cas9 protein (highlight HNH and RuvC nuclease domains) loaded with the sgRNA to form a ribonucleoprotein complex scanning DNA. Panel 3, "DNA Cleavage," illustrates the complex unwinding the double helix, R-loop formation, and a blunt double-strand break cut 3 bp upstream of the PAM. Panel 4 splits into two repair outcomes: NHEJ producing error-prone indels and frameshift knockout, versus HDR using a donor template for precise edits. Use a soft white background, distinct muted colors per molecule, thin connector arrows, and small legible sans-serif labels.
