Well, we need two things. Number one, we need that double stranded DNA molecule that contains the gene that encodes for that protein in the first place, the correct sequence of nucleotides. And we also actually need to know the sequence of nucleotides around that area that we want to modify. So in that area where we want to change that codon sequence that codes for glutamate to the codon sequence that codes for aspartate. So we need two things. Number one, a DNA molecule that contains the gene that encodes for that protein.