Now, for DNA polymerase to actually function effectively, it has to have three different things. So A, B and C and D. We simply discuss one important fact about the DNA polymerase molecule. So let's begin with A. So, in the same way that if we want to build a building, we have to have the bricks, the building blocks to build that building, to build a polynucleotide chain, we have to have the dNTP molecules, the deoxy nucleotide triphosphates. And there are four different types of dNTP molecules. We have deoxy adenosine, five prime triphosphate.