I added the light-green boxes.
What do the red arrows and the line with a filled circle on the far left mean? What does the arrow in the middle mean (also just infront of cas9)? Is the purple square to be understood as the RNA section in the B plot (blue arrow)?
The caption is (cited):
The type II-A system from S. pyogenes is shown as an example. (A) The cas gene operon with tracrRNA and the CRISPR array. (B) The natural pathway of antiviral defense involves association of Cas9 with the antirepeat-repeat RNA (tracrRNA:crRNA) duplexes, RNA co-processing by ribonuclease III, further trimming, R-loop formation, and target DNA cleavage. (C) Details of the natural DNA cleavage with the duplex tracrRNA:crRNA.