So this is a structure, chemical structure of triglycerides. And what might be helpful is to know, think about this word itself. Glyceride is referring to the glycerol backbone, which are just carbon units.
And tri is standing for three fatty acids that are attached to this glycerol backbone. So what's important to know about triglycerides is that that the fatty acids that are on the triglycerides vary based on the chain length and also the number of double bonds. And what's important to know about carbon is carbon has four, it likes to attach to four different things. And this makes a difference in how we actually think about these fatty acids.
So I'm going to show you this on the next slide. So here we're looking at specific fatty acids. So remember, each one of these on this glycerol backbone is a fatty acid.
So in A, we can see that it has a double bond. And what this means is, remember, carbon has four areas it likes to attach to. So in the case of this carbon, one of its areas is attached to another carbon, but it has three extra areas.
In this case, I'm not showing you, but what it's attaching to is hydrogen. Now, when we get to these two carbons, what you can see is that two of the the places or bonds are with another carbon unit. So this carbon, two of its bonds are with one carbon, and then a third bond is with another carbon, and it still has one bond left, which is a hydrogen. But because of this double bond, it now has a point of unsaturation, or it's an unsaturated fatty acid.
Anytime you have a double bond, it's an unsaturated fatty acid. In this case, we only have one double bond. So this is a monounsaturated fatty acid.
In B, we can see there are no double bonds. So this means that each of these carbons is saturated as much as possible with hydrogen. So they are bonding. For instance, this carbon here is bonding in one spot to another carbon and in the second spot to another carbon. But it still has two free open spots where it can bind to hydrogen.
And all of the carbons in this fatty acid chain have single bonds between the carbon units making it a saturated fatty acid. Now this one we can see there are two points of unsaturation or two double bonds. And this means that when there's two or more double bonds, this is a polyunsaturated fatty acid. Poly meaning many.
And then finally D is a monounsaturated fatty acid because we only have one double bond. So the next question that was asked was, what's the difference between a short or medium chain fatty acid and a long chain fatty acid? The answer to this is the number of carbons in the fatty acid chain.
So let's just count the carbons. So in A, we have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 carbons. Remember that any carbons, a carbon chain of 10 or 12 below would be considered a short or medium chain fatty acid. Anything above is a long chain fatty acid.
So this one would be considered a short or medium chain fatty acid. Now B has 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 carbons. 18 carbons makes it a long chain fatty acid.
C has 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 carbons, making it a short slash medium chain fatty acid. And the last one, D, has 1, 2, 3. four, five, six, seven, eight, nine, 10, 11, 12 carbons, again, meeting at short or medium chain fatty acid. So why these are important are really related to digestion and absorption.
So be sure to watch that video to understand why we care if fatty acids are short, medium chain, or long chain when we're thinking about digestion and absorption of fatty acids.