In this video, we're going to briefly introduce 2 other classes of lipids, the steroids and the waxes. Steroids are a complex class of lipid that look a lot different than the other lipids that we've talked about. That's because steroids are not made up of fatty acids. Instead, steroids are lipids that are made up of 4 fused carbon ring structures. A classic example of a steroid is the molecule cholesterol, which you may have heard of before because cholesterol is a common steroid that's important for the structure of animal cell membranes. If we take a look at our image down below on the left-hand side, notice that this molecule we're showing you is cholesterol, and it is a steroid because it has these 4 fused carbon ring structures that we have numbered 1, 2, 3, and 4. Cholesterol is a common steroid important for the structure in animal cell membranes.

Over here on the right, we're showing you a zoom in of an animal cell membrane. One of the major components of cell membranes, as we learned in our last lesson video, are the phospholipids, which we're showing here. Embedded within the cell membrane, and within these phospholipids, are these cholesterol molecules. You can see the cholesterol in the positions that we see here. We'll talk more about the actual function of cholesterol in the cell membrane later in our course when we focus specifically on the cell membrane. This here concludes our introduction to steroids.

Now the other class of lipid that we're going to briefly talk about are the waxes. Waxes are another class of lipid that can be used for protection purposes and also for the prevention of water loss. If you take a look at the image over here on the right-hand side, what we're showing you here is a structure that is a classic example of a wax, and that's because this structure is beeswax, which is why we're showing you a bee over here. Beeswax is made up of a fatty acid. You can see a fatty acid embedded in here, but it also contains another molecule over here that used to be a long-chain alcohol group. The idea here is that waxes can be used for protection purposes and prevention of water loss, and you need to know that waxes are a class of lipid. Both steroids and waxes are types of lipids, and that's the main takeaway here of this video. This here concludes our introduction to steroids and waxes, and we'll be able to get some practice in our next couple of videos. I'll see you all there.