Figure 3. CRISPR/Cas as a genome editing tool.
The guide RNA directs the Cas9 endonuclease to target DNA. Modification of the guide RNA sequence allows any DNA sequence to be targeted. The only sequence requirement is the PAM motif NCC downstream of the target site, and a C at the 5′ end of the target site. The double strand break is repaired by non-homologous end joining, leading to a short deletion.