Hey, everyone. In our intro to lipids, let's first talk about where the word lipid is derived. We're going to say here that it's derived from the word lipo, which is a Greek word meaning fat. Now, when we talk about lipids themselves, they represent hydrocarbon-based biomolecules that are hydrophobic, meaning they're insoluble in water due to being nonpolar. Now we're going to say that they are very diverse structurally and functionally. We'll see how they can be broken down further from Lipids. Now, one of these breakdowns is fatty acids. Fatty acids are long unchained hydrocarbon chains with a carboxylic acid at one end. And we're going to say here that lipids can be categorized based on the presence or absence of fatty acids. If we take a clear look at this chart, we're breaking down lipids. We have our steroids to the right. Steroids are indicative of these 4 fused cells. Steroids themselves can be broken down into cholesterol, bile acids, and steroid hormones. When we get to the steroid section, we'll go in greater detail on these other three breakdowns. Now, fatty acids themselves represent this portion here. Again, it's a long hydrocarbon chain with a carboxylic acid at the end. It can be broken down further into 4 other things. We have our waxes, which are going to give us our alcohol esters and fatty acids involved. We're going to have our glycerolipids. This can be broken down into our Triacylglycerols, which is just a glycerol molecule that has 3 fatty acid chains branched off of it. Next, we have our Glycerophospholipids which are grouped together with our sphingomyelins. Now here, this is also part of our sphingolipids here which are also broken down into our glycolipids. Now, if we take a look at the similarities of what's in the dotted purple box, these are our phospholipids. So, a phosphate group and our lipids together. We can see that there are some similarities, both of them have our phosphate group connected to an amino alcohol. Again, this is just a quick overview of the main components of this group. We'll go in greater detail when we get to these sections. So, they both have this in common. They also have a fatty acid in common. The difference is our Glycerophospholipid also has an additional fatty acids and it's all connected to a glycerol molecule. Over here though, we have our sphingosine, which is our base group, and our fatty acids and phosphate group, and amino alcohol are attached to that. Finally, we have our glycolipids here, which we have also a sphingosine, but we have a fatty acid and a sugar that's attached. Finally, our fourth group, this is our eicosanoid, which is represented by this long carbon chain as well, but it has portions of pi bonds, so it has unsaturated portions. And then at the end again, we have a carboxylic acid. So as we can see, lipids form the umbrella term for all of these diverse groups that have some similarities, but also have some great differences when you're comparing different groups to one another. So as you go through this idea of lipids, we're going to cover these different types of characterizations.
Intro to Lipids - Online Tutor, Practice Problems & Exam Prep
Intro to Lipids Concept 1
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Intro to Lipids Concept 2
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Now remember, we said that lipids can be very diverse structurally and functionally. Here are some primary lipid functions: we have our energy source and storage when it comes to certain types of them. Next, we're going to discuss insulation and protection. When a person is shivering, lipids can help provide insulation to keep us warm. Next, we have Bio Signaling. We can utilize them to communicate between different biomolecules within a living system. And then finally, we have our cell membrane structure. Some of these diverse forms of lipids form integral parts of different types of cells, in terms of their cell membranes. They help with the transportation of nutrients into the cell. It helps with the passage between membranes of ions and different types of helpful components for any type of biological system. Alright. So, these are just some of the main primary functions of a lipid.
Intro to Lipids Example 1
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Which of the following statements about lipids are not true? Steroids are a class of lipids which do not contain any fatty acids. Yes. That's true. Remember, the first branching off of lipids are our fatty acids and our steroids. If steroids contain fatty acids, they wouldn't be different from fatty acids themselves.
All lipids are insoluble in nonpolar solvents, but soluble in polar solvents. So remember, these lipids, many of the lipids contain fatty acids, which are long carbon chains. Those long carbon chains make them nonpolar, which would mean that they are soluble in nonpolar solvents and insoluble in polar solvents. This statement here is false, so this is our answer.
If we look at our other options, certain lipids play an important role as components of biological membranes. That is one of the primary lipid functions that do exist, so this is true.
Lipids contain large numbers of nonpolar Carbon-Hydrogen bonds making them overall nonpolar. This is true. A lot of these lipids contain fatty acid chains which are just carbon-hydrogen bonds which are nonpolar. So overall they're nonpolar.
Steroids themselves also contain fused carbon rings. Those are also sites of being nonpolar. So here the only statement that's false will be option B.