 By now, you hopefully understand both the physics, the free energy, enthalpy, and entropy, the building blocks, amino acids, and how they create alpha helices and beta sheets, and you'll be able to integrate all that to understand when things are stable and why they are stable. Today we're going to take the next step and turn this into actual large protein structures. Proteins are a universe. This is an old illustration from Helmut Grubmühle in the Max Planck Institute in Göttingen, where he rendered all the proteins and then fitted it to the fetus shape. The idea with this is that there are building blocks, there are world, just as the periodic table of the elements is the toolbox of a chemist, organic chemist, for instance, has. This is the building blocks we're going to have in life science. They accomplish virtually everything in our bodies. It's a remarkable diversity we get from those simple 20 amino acids and seemingly simple structures. Don't, for a second, think that that means that life science is simple. It isn't. And yet all this is governed by the laws of physics, and that's the connection we're going to try to make. How have these things evolved in nature to accomplish the structure we're seeing? So we're going to be looking at this both today and in the next lecture, and I'm going to separate these into three large areas, two of them which we're going to cover today. First, we're going to be looking at water soluble proteins, and we typically refer to them as globular. I'm going to bring that up again once we start talking about them. For now, you're just going to think of them as water soluble. The second part is actually the one area where we're going to have a bit of an extension and not talk about proteins but lipids. This is an area I originally did my PhD in, in particular in terms of simulations. Lipids are not formed by amino acids, right? They're small, simple, antithatic compounds that have one water soluble and one fat soluble side. And that gives them the properties of creating membranes on the other ones when we just throw them in solution. All your cell walls are lipids. The reason I'm going to bring them up here is not just because they're interesting as lipids, but we have some of the most important proteins in our bodies, membrane proteins that are embedded in the lipids. And whereas these are water soluble, these have to be fat soluble, at least on the side. But that's such a fun area and the one I'm doing research in. So we're going to cover that separately and lecture it. The area I'm going to start with today is this one. It's possibly something that you haven't associated so much with proteins, but they're the fibrous proteins, the large building blocks of repeating units that we see all over our body. And while they might not seem as fancy and biological, let's say membrane proteins, they are. They're super interesting and they're possibly the most interesting ones from a bio-memetic point of view if you want to use this in bioengineering to build materials. So I'm going to suggest that we start looking at them and then in the second half of today's lecture I'm going to continue with the globular proteins and then we'll save it the best for last, but I'm biased.