So, once again, the important step of this procedure is to create a short DNA primer that is complementary to the side to be altered. However, this primer should be changed in a way to make sure the protein will contain aspartate instead of glutamate. And notice that even though one of the bases are mismatched, the DNA primer will still uneal to that DNA molecule because all the other bases are paired up correctly, assuming we also use the correct temperature conditions. Now, this DNA primer with that mismatched base, also known as a point mutation, can now be used to synthesize the protein of interest, as we'll see in just a moment. So this base pair mutation is known as a point mutation because we essentially mutate our base at a single point, we exchange an A for C. And that's exactly why we call this site directed mutagenesis, because we make this point mutation at that single site. Now, the reason we also call it a ligonucleotide directed mutagenesis is because this DNA primer that we create in this particular case, it consists of these 50 nucleotides that describes an oligonucleotide molecule.