Figure 1.

The mechanism of CRISPR-Cas9 genome editing system. Briefly, RNA-guide nuclease (RNG) is introduced into the organism, and the gRNAs are targeted to the target sequences after recognition by the PAM sequence. Two main repair methods are HDR and NHEJ, the application of which is depended on whether there is a donor sequence. After that, indels are induced for maintaining the liveness of cells. The regions complementary to the gRNA variable region are coloured in red in the bottom box. The insertion regions and PAM sequences are marked in green and blue, respectively. Short dash line represents the deletion region.