Jennifer Doudna: CRISPR is really a fabulous tool for doing surgery on DNA, and it’s basically a way to alter the code of life.  It’s a way to change the DNA sequence in cells so precisely that we can now alter a single letter in the code of a human cell.  A human cell has six billion individual letters — three billion base pairs of those letters.  We can change a single one with this technology and do other things as well.  So I think that this has given scientists a way to rewrite DNA that provides opportunities both for fundamental research to understand what the DNA code is telling us about the way life is, as well as to — in the future — do things that will probably correct disease-causing mutations, create plants that are better adapted to their environments, and many other things.