Lipids | Fats, Steroids, and Phospholipids | Biological Molecules Simplified #4

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Lipids are more then just fats! And Fats are more then just the excess weight we gain as we make poor diet choices. Ironically steroids are also a lipid, and they make people buff...

Image Credit: OpenStax Biology

Thanks for stopping by, this is 2 Minute Classroom and today we are talking about lipids. If you’ve learned about lipids before, you probably associate them with fats, and while fats are a lipid, so are waxes, oils, steroids and phospholipids.

Lipids are macromolecules made up of long hydrocarbon chains, thus named because they are made up exclusively of hydrogen and carbon. These long hydrocarbon chains give lipids their non-polar property, which means they are not soluble in water. This is why oil separates out from water when mixed.

One of the most common components of certain lipids is the fatty acid. Three fatty acids come together with glycerol to form a larger molecule called a triglycerol or triglyceride. Triglycerides have various functions in the body, but a primary one is energy storage as fat or adipose.

Fatty acids also include saturated and unsaturated fats, trans fats, and the omega fatty acids, but we won’t go into their detailed differences in this video.

Another molecule that incorporates the fatty acid chain is the phospholipid, most famous for its formation of the phospholipid bilayer which protects a cell from outside intrusion. Phospholipids contain two non-polar fatty acid tails bound to a polar phosphoglycerol head. This is why they form a bilayer, because the nonpolar tails are attracted to each other and the heads are attracted to water solutions in and out of the cell. At some point I’ll make a video discussing just how awesome this cell membrane is.

Let’s talk about steroids next. And yes, this includes these type of steroids, but that is not the focus of this video. Steroids are hydrophobic and not water soluble like the other lipids, but they do not contain fatty acids. Instead, they have four cyclic rings linked together. This basic structure is then added to to give us common steroids like cholesterol and cortisol. Steroids have many functions throughout the body, including the presence of hormone steroids like progesterone and testosterone, both formed from cholesterol.

Finally, lets not forget about waxes. Waxes have a variety of unique structures, and are found in the feathers of some birds and leaf structures of many plants. This is why water beads up or runs off certain plants.

There is a lot more to lipids, we didn’t even talk about soaps and detergents, but this was a great overview. If you have additional questions about lipids or just want to show some love, comment below!

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I’ll catch you next time.