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. Now the problem is ourselves don't actually use that code directly to form the protein. So we don't simply form proteins from DNA. What must happen is we have to first translate or transcribe that genetic code into a code that is readable and can be understood by that cell and that is where RNA comes into play.