The CRISPR system in bacteria involves repeats derived from viral DNA and genes coding for nucleases that cut DNA or RNA.

“there were also other researchers who began to zero in on a group of genes so these are things that are telling the bacteria to make certain types of protein there are these certain genes that are right next to the repeats and it took a while for people to begin to associate the genes and the repeat to to be know together as as one uh single system but um the people who are studying the genes realize that these genes were carrying uh nucleases so nucleases are proteins that usually go and cut up either DNA or RNA”