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. Now, once we form them, it's the hydrogen bonds that exist between the NH group of one amino acid and the co group of another amino acid that stabilizes these structures and allows them to exist for an extended period of time. Now, let's focus on this amino acid here. So we see that we have this NH group of this amino acid here that interacts with the co group of this amino acid here.