 Let's get back to this whole snorkeling sticking out concept and if I look at that snapshot this is roughly what it would look like. That lysine sidechain, do you remember seeing in the simulation how this pretty much never changed? It stayed stuck in a way. Well it's not exactly stuck but we can calculate the average angle. This would be zero degrees so the question is how much are we sticking up here on average? This concept is called snorkeling and we occasionally see that in structures of proteins. At charts or positively or negatively charts or polar sidechain we prefer to snorkel out to the aqueous the hydrophilic parts. Let's look at this and example those. You don't have to trust me your basis in computer simulation. This is a relatively large protein with a transmembrane domain. It doesn't matter what it does. I think it's one in IK if you want to have a look at it in the PDB. I'm really only interested in the transmembrane domain here. This is the transmembrane domain. We have two chains up here and we have a few gray lipids. I'm not going to talk about the lipids but that's how you see that it's the transmembrane part. You also see that the transmembrane part consists entirely of alpha helices. Let's magnify that one and look just at that part and I'm going to ignore the lipids for a second here. There are two interesting residues in this particular protein. First we have a lysine. Do you see the shape of that lysine? This is not based on a molecular simulation. This is a structure in an x-ray structure in the protein data bank. This x-ray structure the reason why we can see that is that it's a diffraction pattern from a crystal of billions of billions of billions of billions of identical copies and in every single such copy this lipid will stretch out because we have all the lipids here. The lipids is also effectively bound to the structure. That's why we see it. That's because it's a charred cyan chain that's snorkeling. I'll write that here. We snorkeling. But we have another side chain up here. Do you see what this side chain does? This is an aromatic ring. It's a phenylalanine so it's a hydrophobic aromatic residue but this one is pointing in the opposite direction which makes sense. This is something that is purely hydrophobic. It will definitely only want to interact with the lipid chain. So this particular residue we say that it is anti snorkeling. These are important concepts to understand. We see them in proteins now and then and in particular it's something that we can use in protein design later on and in particular to understand how the membrane proteins work.