In the case of DNA, the individual subunits known as nucleotides bond to one another via bond, known as a phosphol diaster bond. So let's take a look at the following molecules. So we have one nucleotide and a second nucleotide. And notice that these two nucleotides bond to one another via the phosphol diaster bond. So we have the phosphorus atom and we also have the two aster bonds shown here. And that's exactly why it's called a phosphodia ester bond.