Targeted genomic cleavage requires two key elements: a homing device and an endonuclease. The homing device in the CRISPR/CAS platform is guide RNA, or gRNA, and a CAS nuclease.
The gRNA contains a twenty-nucleotide target sequence immediately upstream of a Protospacer Adjacent Motif or PAM, linked to a tracrRNA scaffold. This is sufficient to direct the CAS9 nuclease to the complementary site in the genome and create a double-stranded break.
Compared to previous genome editing methods, such as ZNF and TALEN, CRIPSR/CAS is cheaper, quicker, and more accessible for researchers.
Due to its amazing simplicity, CRIPSR-based genome editing can be achieved with a simple transfection.