Now, if we repeat step number three and step number four many times, we essentially can add many of these amino acids onto our growing polypeptide chain. So each time we essentially want to remove the TBA group and then we want to add this molecule here. So for instance, in the next step here, we say repeat many times. But in the next step, we once again mix this molecule with CF three COOH our trifloroacetic acid, a dilute acid. If we mix it with this, that will remove the TBA group. And then we mix this molecule minus the TBA group with this amino acid and that will form a tripepptide.