Question

What type of organism makes restriction enzymes?
How did restriction enzymes evolve?
How do scientists use restriction enzymes?
If you digest an entire human genome with a restriction enzyme you get a blurry smear in the lane of the gel. Why?

I have a quiz tomorrow on electrophorosis, VNTR, PCR and DNA fingerprinting and those are all questions from a lab i didn't finish. If u know any of those answers it would be helpful!!