And it's the primary structure, it's the sequence of amino acids that actually determines what the final structure of that protein is. And that's a very important point to remember. It's the primary structure, it's the specific sequence of amino acids in that polypeptide that determines the final three dimensional structure of that polypeptide. So let's suppose we have the following five amino acid polypeptide. So let's begin on the left side. So we have amino acid number one.