It will form these base pairs as shown in the following diagram. So T base pairs with a G, base pairs with C, and C base pairs with G. And then the DNA polymerase will bind onto the primer and it will use the hydroxyl group on this cytosine to basically form that first phosphodiaester bond. And so it will take a thymine. It will take this molecule here to basically form the first base. Then it will move on onto the second base, which is a T, and that will basically form an A. Now, we have two types of A's that we can use.