Comprehensive Final Lipid Map: Study with Video Lessons, Practice Problems & Examples

Lipids are categorized into fatty acid-based and isoprene-based lipids. Fatty acids, with structures like saturated and unsaturated types, form glycerolipids (e.g., triacylglycerols for energy storage) and sphingolipids (e.g., sphingomyelin in nerve cells). Eicosanoids, derived from 20-carbon fatty acids, include prostaglandins, thromboxanes, and leukotrienes, which play roles in inflammation and muscle contraction. Isoprenoids encompass terpenes, steroids (like cholesterol), and lipid vitamins (A, D, E, K), crucial for various biological functions, including hormone synthesis and cellular signaling.

Comprehensive Final Lipid Map

In this video, we're going to do a review of all the lipids that we've covered so far by analyzing our comprehensive final lipid map. And so what you see here on this page is our comprehensive final lipid map, which you'll notice looks a lot like the lipid map that we showed you guys early on in this lesson on lipids. And really the big differences are that here we have some additional images and some additional text to help you guys remember important features about these lipids. And so the idea here is that you can use this comprehensive final lipid map here to complement your studying and help remind you of important features about these lipids. Alright. So that being said, let's go on and get started with our comprehensive final lipid map. And so, we know that lipids are immediately branched into 2 groups, The fatty acid base lipids over here in the left branch, and the isoprene based lipids over here with the right branch. And so we're gonna review the fatty acid base lipids first. So recall that fatty acids are just long hydrocarbon chains like this one with a carboxylic acid group at the end. And there are many different types of fatty acids, including saturated, unsaturated, and omega fatty acids, which recall omega fatty acids are essential and required in the diet, and they're commonly found in fish. Now recall that the alpha carbon of a fatty acid is the carbon atom that is adjacent to the carboxylic acid carbon over here. And recall that the omega carbon atom is the carbon atom that is furthest away from the carboxylic carbon atom over here. And also don't forget about the nomenclature of these fatty acids, the shorthand naming system specifically. Which all we need to do is count the total number of carbon atoms in the fatty acid, which in this fatty acid, there are 16 carbon atoms. And then count the total number of double bonds, which in this fatty acid, there's 1 double bond in the hydrocarbon chain. And then indicate the position and location of that double bond with a delta exponent. And so counting from the carboxylic acid carbon over here, the double bond, notice, appears at carbon number 8. And so the shorthand naming system for this fatty acid is 16 1 Δ 8 . Now there are really 4 major classes of fatty acid based lipids, which we have as glycerolipids, sphingolipids, waxes, and eicosanoids. Now recall that the Glycerolipids are literally lipids with a glycerol molecule as the form and the fatty acids that are in these glycerol lipids are typically ester linked. And there are really 2 types of glycerolipids that we had talked about. The triacylglycerols and the glycerophospholipids. Now the triacylglycerols with the tri prefix have 3 fatty acids that are Ester linked to the glycerol molecule. And we talked about these functioning specifically as long term energy storage molecules. And so just like batteries act as long term energy storage, these triacylglycerols also act as long term energy storage. Now, the glycerophospholipids notice are falling into this pink box that we have here, which are labeling our phospholipids and phospholipids are just lipids with phosphate groups that are covalently attached. And so, glycerophospholipids are specific types of phospholipids that have a glycerol backbone as the platform. Recall that phosphatidates are the simplest glycerophospholipid because they do not have a variable head group attached. And simply by attaching all of these different variable head groups here, we can get different classes of Glycerophospholipids. And the main, indicator of a Glycerophospholipid is this prefix phosphatidyl, which is saying that it has the phosphatidate backbone and some varying branching variable head group. Now what's important to note is that phosphatidylcholine is actually the most abundant Glycerophospholipid found in membranes. And so what you'll notice is that these phospholipids here are being branched into these biological membranes, and we'll talk more about biological membranes later in our course. So moving on to the sphingolipids which is our second type of fatty acid based lipids. These are lipids that have a different platform. Instead of having a glycerol molecule as the platform, sphingolipids have a sphingosine molecule as the platform. And sphingosine molecules will actually attach their fatty acids via amide linkages instead of ester linkages. And so the amide linkage here is key, which is why it's here in our text. Now there are 2 major types of sphingolipids that we had talked about, the sphingophospholipids and the sphingoglycolipids. The sphingophospholipids are another type of phospholipid that again use a different platform, which is the sphingosine platform, and we talked about one specific sphingophospholipid, which was sphingomyelin, and that is commonly found in the myelin sheath of the membranes that surround our axons of our nerve cells. And so here we have that image of our axon of our nerve cell to help remind you that sphingomyelin are found in the myelin sheath. Now the sphingoglycolipids are glycolipids with a sphingosine backbone. Now, be careful not to confuse the prefix glyco with the prefix glycero. Glycero, of course, means that it has a glycerol platform, and glyco is referring to carbohydrates or sugars. And so, these are our glycolipids, lipids that are covalently attached to sugar units. Cerebrosides only have one single sugar unit attached, and these are commonly found in our brains. And, globocytes, they have 2 or more sugar units. And then gangliosides are a specific type of globocyte where they have a complex oligosaccharide attached that have multiple sugars and a sialic acid residue, which is this orange residue that we're labeling here, commonly NEU 5AC. Now these gangliosides, they are associated with Tay Sachs disease. And so if there are metabolism defects with the gangliosides that will lead to this neurological disease called Tay Sachs disease. So the next fatty acid base lipid that we have are the waxes and waxes we know are fatty acid chains or FA for short and long chain alcohol groups, or LCA for short. And, the fatty acid and long chain alcohols are ester linked together to create the wax. And the wax that we had talked about in our previous lesson videos are, was beeswax. So, that is why we have that here. Now the 4th and final type of fatty acid base lipids that we have are the eicosanoids. And recall that the prefix eicosi is, a Greek prefix that means 20. And so eicosinoids are derived from c 20 polyunsaturated fatty acids, like arachidonic acid, which is, again, a fatty acid itself and explains why eicosanoids are fatty acid based lipids. And there are 3 different types of eicosanoids. There are the prostaglandins, the thromboxanes, and the leukotrienes. Recall that the p in the prostaglandins reminds us that it has a cyclopentane ring, like the one that we see down below. And prostaglandins, we said, have lots and lots of different types of functions. But one of their primary functions includes the regulation of pain, inflammation, and fever.

Here’s what students ask on this topic:

What are the main types of fatty acid-based lipids and their functions?

Fatty acid-based lipids are categorized into four main types: glycerolipids, sphingolipids, waxes, and eicosanoids. Glycerolipids, such as triacylglycerols, function as long-term energy storage molecules. Sphingolipids, like sphingomyelin, are essential components of the myelin sheath in nerve cells. Waxes, composed of fatty acids and long-chain alcohols, provide protective coatings in plants and animals. Eicosanoids, derived from 20-carbon fatty acids, include prostaglandins, thromboxanes, and leukotrienes, which play roles in inflammation, blood clotting, and muscle contraction.

How are glycerophospholipids different from sphingophospholipids?

Glycerophospholipids and sphingophospholipids differ primarily in their backbone structures. Glycerophospholipids have a glycerol backbone with fatty acids ester-linked, and they include a phosphate group. They are major components of biological membranes. Sphingophospholipids, on the other hand, have a sphingosine backbone with fatty acids amide-linked. An example is sphingomyelin, found in the myelin sheath of nerve cells. Both types are phospholipids but differ in their structural platforms and linkages.

What roles do eicosanoids play in the body?

Eicosanoids, derived from 20-carbon polyunsaturated fatty acids like arachidonic acid, play crucial roles in the body. Prostaglandins regulate pain, inflammation, and fever. Thromboxanes are involved in blood clotting and are found in platelets. Leukotrienes function as strong biosignals that cause smooth muscle contraction in the lungs and are associated with asthma and allergic reactions. These molecules are essential for various physiological processes, including immune responses and maintaining homeostasis.

What are the different classes of isoprenoids and their functions?

Isoprenoids are categorized into three main classes: terpenes and terpenoids, steroids, and lipid vitamins. Terpenes and terpenoids, such as squalene, are involved in various biosynthetic pathways. Steroids, like cholesterol, serve as precursors for steroid hormones (e.g., testosterone and estradiol) that regulate sexual characteristics and other physiological functions. Lipid vitamins (A, D, E, K) are essential for processes like vision, calcium metabolism, antioxidant protection, and blood clotting. Each class plays a vital role in maintaining cellular and systemic health.

How are omega fatty acids different from other fatty acids?

Omega fatty acids are a type of polyunsaturated fatty acid characterized by the position of the first double bond from the methyl end (omega end) of the carbon chain. For example, omega-3 fatty acids have the first double bond at the third carbon from the omega end. They are essential fatty acids, meaning they must be obtained through the diet, commonly found in fish. Omega fatty acids are crucial for brain function, reducing inflammation, and lowering the risk of chronic diseases like heart disease.