And GAA would code for the glutamate amino acid in that protein. But instead of creating a DNA primer with the correct GAA sequence, we can create a DNA primer that contains a mismatched base. Instead of having an a here, we can place a c. And so instead of having GAA that codes for glutamate. We simply modify this last nucleotide in the codon sequence and we form GAC. And we know from the genetic code that GAC codes for aspartate, which is the amino acid that we want to build in the first place. And notice that because C will not pair up with tea, no hydrogen bonds are actually formed between these two nucleotides.