Now the question is, how exactly does the polypeptide begin to twist to form these four different types of structures? Well, inside the polypeptide, we have different bonds. Now, the peptide bonds are the bonds holding the amino acids inside the polypeptide together. And these peptide bonds have a double bond character. And what that means is they don't actually rotate, but all the other single bonds inside the polypeptide chain do rotate. And it's the rotation of these other single bonds inside the polypeptide chain that allows the linear polypeptide to eventually fold into the beta pleated sheet, into the alpha helix, into the beta turn and our omega loop.