I need some help about Crispr / Cas9. The CRISPR/Cas9 technic consists (for bacterias) in "cut" bacteriophage's DNA, in order to make it unfunctional. When the RNA is transcribed (RNA which is complementary to the bacteriophage's DNA), it will be associated with crRNA and tracrRNA to form the sgRNA (single guide RNA). But I would like to know where crRNA and tracrRNA are from? and what are their function(s)/ goal(s).
Sorry If I made mistakes I'm French.