Figure 1.

a) The crRNA from the CRISPR array combines with a smaller tracrRNA molecule, becoming a gRNA complex. b) The gRNA binds with a Cas9 protein, forming a gRNA:Cas9 complex. c) The gRNA guides the Cas9 protein, targeting a specific DNA sequence, which it first recognizes by the PAM motif. The RuvC and HNC nuclease sites cuts the target sequence, leaving two homologous blunt ends. d) The desired DNA repair template inserts the desired gene and repairs the strands by HDR, the product DNA then undergoes adaptation into the organism’s genome.