• Clustered Regularly Interpsaced Short Palindromic Repeat (CRISPR) → form from adaptive immune system in bacteria, modified for genome engineering → before CRISPR< sicentifists had to genereate a new nuclease pair for every genomic target, CRISPR is relatively simple and adaptable
• CRISPR contains guide RNA (sgRNA) and endonuclease (Cas protein) → gRNA is short synthetic RNA composed of a scaffold sequence necessary for Cas-binding and user-defnined 20 nucleotide spacer that defined genomic target
  • one can change genomic target by chainging target sqeuence in sgRNA
• employed to knock out target genes in various cell types, modifications in system now allow it to selectively activeate/repress target genes, purify specific regions of DNA, image DNA in live cells, and edit DNA or RNA