So because we were able to determine the structure of nucleic acids we were able to basically determine the fact that we have the base pairing system and that allowed us to understand how transcription actually takes place. And then we were able to determine the fact that ribosomes use the genetic code to basically translate the sequence of nucleotides on the RNA into the sequence of amino acids on the protein because we were able to determine how these viral agents use nucleic acids to infect cells and then hijack the cell machinery to make many copies of that virus. So because we were able to withstand these nucleic acids that exactly where the field of biotechnology actually came from. And more specifically, there are six key factors that played a role in basically allowing this biotechnology field to actually arise. So let's briefly discuss what these six factors are and in the next several lectures we're going to take a look at these factors in much more detail. So let's begin with factor number one the existence of restriction enzymes.