In this video, we're going to introduce fatty acids. Fatty acids are defined as hydrocarbon chains of varying length with a carboxylic acid functional group at the very end. We'll be able to see some examples of fatty acids down below when we get to our image. Now there are two main types of fatty acids that you all should know. The first main type is the saturated fatty acids, which, as their name implies, are fully saturated with hydrogen atoms. This is because they only contain carbon to carbon single bonds that allow them to be fully saturated with hydrogens. Saturated fatty acids tend to be solids at room temperature. Let's take a look at our example down below at the saturated fatty acids, which we have over here on the far left-hand side. These are saturated fatty acids because notice that the hydrocarbon chain that we have here is only made up of hydrogens and carbon atoms; they're fully saturated with hydrogens. They have the maximum amount of hydrogens on them because notice that the carbon-carbon bonds in here only contain single bonds as we mentioned above. Notice that this hydrocarbon chain here at the very end, it has a carboxylic acid group which is right here. It's basically a carboxyl group. That is why this is a fatty acid, and it's saturated. Notice that over here, this is another way to represent the hydrocarbon chain where each of these corners that you see here, each of these points represents a carbon atom, and notice that the hydrogen atoms aren't being shown. It's just another representation of the same exact molecule. Once again, saturated fatty acids tend to be solids at room temperature, just like this butter up here. Butter, of course, is solid at room temperature, and so that is a source of saturated fatty acids.

The second main type of fatty acids that you all should know are the unsaturated fatty acids. As their name implies, they are not fully saturated with hydrogens. The reason they're not fully saturated with hydrogens is that they have the presence of at least one carbon to carbon double bond. The double bonds in the hydrocarbon chain create a bend or a kink in the chain. The kink in the chain ultimately makes these unsaturated fatty acids liquids at room temperature instead of being solids. When we take a look at our image down below over here in the middle, notice what we're showing you is an example of unsaturated fatty acids, and notice that the hydrocarbon chain that we have here is not fully saturated with hydrogens because there is a carbon to carbon double bond, and so they are missing some hydrogens here at these positions. That's why they call them unsaturated because they're not fully saturated due to the presence of a double bond. Notice that the double bond also creates a bend in the chain. It's not straight or linear like the saturated fatty acids are. It creates a bend or a kink in the chain. Because it has a kink in the chain, the unsaturated fatty acids cannot be tightly packed together, so they're going to remain relatively loose. That loose nature is why they are liquids at room temperature. These oils, such as vegetable oils and olive oil, are examples of unsaturated fatty acids that are liquids at room temperature.

There is one subset of unsaturated fatty acids called trans fatty acids. You may have heard of trans fatty acids or trans fats before, and really these are a subtype of unsaturated fatty acids. That's why we have them grouped in the same grouping as unsaturated fatty acids. Trans fats are artificial unsaturated fatty acids. They do not have a kink in their chain despite having a double bond. Let's take a look at the trans fatty acid, which we have down below right here. Notice that the trans fatty acid does have a double bond in its chain. However, notice that the double bond that's in the chain of the trans fatty acid does not create a kink in the chain or a bend in the chain like other unsaturated fatty acids. Trans fatty acids specifically are going to have straight chains despite having a double bond in them. Again, trans fatty acids are artificially made, and so you'll find them in foods like burgers, french fries, and similar items. That's why we have this image right here. Trans fatty acids usually are associated with being very unhealthy. This is typically the type of food that you would want to try to avoid in your everyday diet.

This here concludes our introduction to fatty acids and the difference between saturated and unsaturated fatty acids. We'll be able to get some practice moving forward in our course. I'll see you all in our next video.