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. Number two, to know the nucleotide sequence on that gene around the side that is actually to be altered. Now, the important step in this procedure is to basically create a special DNA primer that is complementary to the nucleotide sequence along that gene where we want to make that alteration. And the way that we want to build the DNA primer is we want to change the sequence in that DNA primer so that we change the codon that goes from glutamate to the codon that codes for aspartate.