So let's suppose that this is our amino acid that we're actually examining. So this is our amino acid, and this green bond is the peptide bond that does not rotate, that connects this amino acid to the next amino acid. Then we have this peptide bond that connects to this amino acid and so forth. So remember, these green bonds are peptide bonds. And because those peptide bonds are resonant stabilized, they have a double bond character and they will not rotate. But these other bonds are single bonds and they do rotate, and it's their rotation that allows this helix and the other structures of the secondary structure to actually form in the first place.