in this video, we're going to do a quick refresher on lipids, so recall that lipids are a major class of macro molecule that all living cells contain. And lipids are incredibly diverse in both their structures as well as their functions. And that makes him a little bit challenging to group together and to talk about. But one thing that all lipids have in common is that all lipids are hydro phobic and so recall from your previous biology courses that the root hydro means water and that phobic or phobia means fears. And so hydrophobic means water fearing. And of course, this means that they don't dissolve very well with water or mix well with water. Now, examples of lipids include fossil lipids, fats, oils, waxes and steroids. And in our example below, What we're gonna do is match each of these lipids with their corresponding description and function in the blocks below. So the first block says major component of cell or plasma memory and recall from your previous bio courses that this is the fossa lipid. Now the next block says, uh, long term energy storage, but specifically in plants. And so these are our oils and like in the images below. Vegetable oils and olive oils are extracted and produced by plants, and they tend to be liquids at room temperature. Now if we compare that directly to the next block, which is long term energy storage, But in animals, these are going to be our fats. And so fats are extracted and produced by animals, and they tend to be solids at room temperature. And so you can think of a stick of butter, for instance, for this example. Now, in our previous videos, we talked about how carbohydrates are used as short term energy sources. And so all that saying is that cells typically use their short term energy sources first, so they use their carbohydrate energy sources. And then, once those air depleted, they'll turn to use their long term energy sources, such as fats and oils. Now, next block, it says sex hormones, and this includes estrogen and testosterone, and it also includes components of plasma member in such as cholesterol. And from this image, you can get a quick glimpse at how these are structurally diverse group of lipids, and these are, of course, thes steroids. Now, the last block is says protection and prevention of water loss. And this includes bees, wax and earwax. And of course, this has got to be the waxes. And so, in our next video, what we're gonna do is talk about a very biologically important lipid. And this is the fossil lipid. So I'll see you guys in that video.

so fossil lipids are biologically relevant lipids that are anti empathic and so recall from your previous biology courses. All this means is that they contain both a hydra filic and a hydrophobic part, and we covered hydrophobic in our previous videos, which again means water, fearing so hydro filic means the complete opposite. Water loving and so fossa lipids contain a polar hydro filic head and non polar hydrophobic tails, where the tails are hydrocarbon chains because they're long chains of just hydrogen and carbon atoms and the anti path IQ nature of a foster lipid allows them to form membranes and that allows them to compartmentalize the cell. And we'll talk about the hydrophobic effect later on. In our course. However, what I want you guys to know in this video is that the hydrophobic effect explains how fossil lipids for membranes when they're in aqueous solutions, and so down here. In our example, we have two different representation of a fossil Lippett. On the left, we have a more simplified version, and on the right, we have a mawr chemically structured version, and what you'll see is that possible lipids contain ahead, which is polar hydro and Hydro Filic. And so that head consists of a phosphate group as well as a glycerol molecule and down below. What you'll see is that there are these tales that are non polar hydrophobic tails which are hydrocarbons. And so over here, what you'll see is that we have a fossil lipid and they are able to form membranes when they're in aqueous solutions. So they will continuously clump together on and they conform specific membranes, as you can see in this diagram, and so that transitions us perfectly into our next video, where we're going to talk about cell membranes. So I'll see you guys in that video.

So we already know that all cells contain a cell or a plasma membrane that separates the inside of a cell from the outside or the exterior. And we'll be talking about membranes at different points throughout our entire biochemistry course. But in this video, we're just gonna do a quick review. So recall from your previous biology courses that the fluid mosaic model describes a membranes fluid ity as well as Theus assortment of components that are embedded inside of the membrane, such as, for instance, proteins and recall that cell membranes are semi permeable, which means that they are partially penetrate herbal. Something's can cross the membrane, whereas other things cannot. And that contributes to its functions, such as the transport of materials or bio signaling and typically Onley. Small, non polar molecules such as, for instance, carbon dioxide or oxygen gas are capable of freely crossing the membrane from one side to the other without requiring an input of energy and so down below. What we have is the typical structure of a cell membrane, and I don't want you guys to memorize all of these components. It's more so, a review and a refresher, and so notice that the major component of the plasma membrane is the fossa lipid, which is represented by all of these yellow balls and the brown tales. And they create the foster lipid bi layer, which again is very fluid like. So these fossil lipids can shift past one another, and they can move from one side of the membrane to the other side of the membrane, and the proteins that are embedded inside of it again create a mosaic like look. And so all of these proteins can also shift in the membrane so they're not stationary or stuck. They can move around and squeeze between the possible lipids. And so we have a bunch of different types of proteins. We have channel proteins that allow the passage of materials. We've got peripheral proteins that are on Lee. On one side of the membrane, we've got integral proteins that spanned the whole membrane. We've got, uh, cholesterol inside of the membrane that helps to create make it more rigid, and we talked about how carbohydrates can be attached to different molecules to create glycoprotein and like a lipids, and all of these components come together to create the cell membrane as we know it. And so this concludes our refresher on the cell membrane and I'll see you guys in the practice videos.