Now, we know that this happens because it's the primary structure, it's that specific sequence of amino acids in that polypeptide that actually determines what that final three dimensional structure of that protein actually is. So the protein easily is able to go from that non functional denatural state to the fully functional native state because it's the primary structure that determines the tertiary structure of that protein. Now, the question we want to focus on in this lecture is how exactly does the folding or unfolding process actually take place? How exactly does the protein unfold from the native state into that denatured state? Or how does a protein fold from a denatured state and to that fully functional threedimensional state? So, let's begin by taking a look at the following graph.