Which comes first, PCR or Gel electrophoresis? If I want to find out wither a group of patients have the abnormal BCR-ABL cancer gene, how do I benefit from the PCR and the gel electrophoresis techniques? I'm kinda lost trying to determine which comes first and what is the exact function of each device, I have read the whole gene cloning process in my biology book but couldn't absorb it because it's so complex.

PCR comes first. If PCR works right, then a specific product will be amplified. But you cannot see it in the little plastic Eppendorf PCR tube. That is what the electrophoresis is for. After you run PCR, you run the products on an agarose gel to visualize it (with the help of some flourescent dye). The agarose gel is just to see if the PCR worked.