So once we prepare our amino acids, let's go to step number two. In step number two, we actually want to take that first amino acid in line from the terminal carboxyla and attach it onto that solid surface. So in step two, an amino acid that has been protected as the amino group by Tbock is attached onto a solid surface. And this will be the amino acid found on the terminal carboxyl end of that growing polypeptide chain. So this is our group that will be attached onto the solid surface that will react with the carbon of the carboxyl group of this amino acid number one. Or let's call it amino acid number N, assuming that we have a number of amino acid in that eventual polypeptide chain.