 Here is another beta sheet. Gamma crystalline. Gamma crystalline occurs in the lens of our eyes. So it's a pretty much a transparent protein, and it's partly what happens when our lenses age and we eventually can't accommodate anymore. It's due to hardening of the entire lens where these proteins is one of the properties. I'm not sure if you can see it here, but if you look at the structure, do you see something special in the loops? It's not a simple meander. Actually, if you look at each of these sheets, they have a special property. You're kind of going one up and then you're forming a small loop, but then you're going one step back. It seems like a really stupid fold at first sight, but it's not at all stupid. It's a remarkably beautiful fold. If you look at it, I think it's going to be much easier if I show you a hierarchical plot. So here you see the advantage of not having to worry about a real protein. Do you see here that I'm having here in the middle? I'm starting out with strand one coming from the end there. So I'm having strand one and then I'm making a short turn back to strand two. And then I'm making a short turn to stand three. If I had continued in that direction, this would be in a beta meander. But you see now that I'm making a jump over the first small loop I had into strand four. And then after strand four, I make a jump over two more strands. Now I'm on the blue, the other side, into strand five. But then I make two small turns again. So there's this pattern to short turns and then two long turns or loops or whatever you call them. This is a very special motif that was discovered by Jane Richardson in 1979.