So let's begin with the function of DNA. So DNA molecules are these biological molecules that store that genetic information and the genetic information is stored in the sequence of these nitrogenous bases because the backbone of the DNA molecule that consists of the sugar molecule and the phosphate essentially repeats as we go from one nucleotide to another. That does not change. What does change is the sequence of nitrogenous bases and it's within the sequence of bases where the genetic information is actually stored as we'll see in much more detail in a future lecture. So the first function of DNA molecule is to store that genetic information and keep it readily accessible to the cell. And what that means is if the cell wants to synthesize some type of protein for example hemoglobin or my globin it has to go down to the DNA in the nucleus and get that genetic code that must be used to then create that protein.