Alright. In this video, we're going to explore our first category of lipids, the fatty acids. And so first notice that down below. Over here we have a different version of our original lipid map and you can see that the lipids are going to be broken up into the fatty acid based lipids, which is this entire left branch over here. And then we also have the ice, a prion based lipids, and noticed that the is a prion based lipids are being abbreviated with. This is a pre molecule, and we're going to continue to do that until after we've explored all of the fatty acids lipids in their entirety. And then again, we'll go and explore the Supremes last. And so what in the world are these fatty acids? Well, fatty acids, which are also sometimes generally called just fats. Occasionally, uh, these air just hydrocarbon chains of varying length that have a terminal car box Cilic acid group. And so, if we take a look at our image down below right here, notice we have a fatty acid molecule. We have this long hydrocarbon chain, and at the very end of the hydrocarbon chain, we have this car box Cilic acid just as we described above. Now these fatty acids are gonna be used as building blocks form or complex lipids such as glycerol, lipids, single lipids and all of these other ones down below waxes and a costa noise as well. And so what's important to note is that the carbon atoms of fatty acids they're usually numbered starting at the car boxful, carbon atoms and so notice. Over here we have the car box, a carbon atom, and so this would be carbon number one. And what's also important to note is that the Alfa carbon designated by just the Greek symbol Alfa is going to be the carbon atom that is adjacent or right next to the car boxful carbon atom. And so this carbon atom right here in blue because it's adjacent or right next to the car box, a carbon atom. This is going to be the Alfa carbon atom, and you can think the A in Alfa is just for the A in adjacent right next to and then, of course, the omega carbon atom symbolized by the Greek letter Omega is going to be the carbon atom that is furthest from the car box will carbon atom. And so, of course, this carbon atom over here is the one that's furthest away from the car box, a car box like carbon. And so this is going to be the Omega Carbon. And so what's important to note is that before we actually move onto talking about glycerol, lipids were actually going to talk about fatty acids For a little while, we're gonna talk about different types of fatty acids, such as unsaturated and saturated in our next lesson video. And then we'll talk about nomenclature and some other fatty acids as well. So we're going to stick on this fatty acids for a little bit before we actually get to glycerol lipids. And so this here concludes our introduction to fatty acids. And again, in our next lesson, video will be able to talk about unsaturated and saturated fatty acids. So I'll see you guys there
2
Problem
Problem
Which fatty acid chain would you expect to be least soluble in water?
a) 16-Carbon fatty acid.
b) 4-Carbon fatty acid.
c) 22-Carbon fatty acid.
d) 12-Carbon fatty acid.
A
16-Carbon fatty acid.
B
4-Carbon fatty acid.
C
22-Carbon fatty acid.
D
12-Carbon fatty acid.
3
concept
Fatty Acids
Video duration:
3m
Play a video:
in this video, we're going to differentiate between saturated and unsaturated fatty acids. And so these fatty acids that we've been talking about could be categorized into two different groups based on the nature of their hydrocarbon chains. And these two different groups are again the saturated fatty acids and the unsaturated fatty acids. Now, as the name implies, the saturated fatty acids are going to be fully saturated with hydrogen atoms. And so that means that they're hydrocarbon chains are on Lee going to contain carbon, carbon single bonds, and there will not be any carbon carbon double bonds. And so, if we take a look at our image down below, over here on the left hand side, notice we're showing you an example of a saturated fatty acid and so you can see that it's got a carb oxalic acid and this long hydrocarbon chain and the hydrocarbon chain notice on Lee has carbon carbon single bonds, and that means that the hydrocarbon chain is fully saturated with hydrogen tear. And so over here we have a different three D representation of the same exact fatty acids, and this is actually the fatty acid steer eight, which is the one of the most abundant saturated fatty acids and animals. Now, of course, the second group of fatty acids are gonna be the unsaturated fatty acids, and as their name implies, they are not going to be fully saturated with hydrogen atoms. And this is due to the presence of greater Than or equal toe one carbon carbon double bond in the hydrocarbon chain. Now the prefixes, mono and poly, respectively, indicate the presence of just one or greater than one double bond. And the double bonds that are present and unsaturated fatty acids are almost always in the cysts confirmation, and this is what creates kinks in the chains of unsaturated fatty acids. And so, if we take a look at our image down below over here, notice we're showing you another fatty acid over here. But this is an unsaturated fatty acid, because notice there's the presence of a double bond and notice that the double bond is going to be almost always in the cysts confirmation, which again creates this kink here in the chain of the unsaturated fatty acids and notice that because there's Onley, one double bond that's present here in this specific unsaturated fatty acid, Oli eight. This makes it a mono unsaturated fatty acid, indicating the presence of just one double bond. Now, over here on the right notice that we have another unsaturated fatty acid linoleic, and this one actually has the presence of three double bonds. And so, uh, because it has mawr than one double bond, this would be a poly unsaturated fatty acid. And again, the double bonds air going to almost always be in the cysts Confirmation. And again, this is going to create kinks in the chains of unsaturated fatty acids. And that will be important in our next lesson video when we talk about the melting points of these fatty acids. And so this here concludes our introduction to saturated and unsaturated fatty acids, and we'll be able to get some practice applying these concepts in our next video. So I'll see you guys there
4
Problem
Problem
What is the molecular formula of Linolenic acid, an 18-carbon polyunsaturated fatty acid with 3 double bonds?
a) C18H32O2
b) C18H30O2
c) C28H30O2
d)C18H34O2
A
a) C18H32O2
B
b) C18H30O2
C
c) C28H30O2
D
d)C18H34O2
5
concept
Fatty Acids
Video duration:
6m
Play a video:
in this video, we're going to talk about the melting points of fatty acids. And really, there are two primary factors that affect the strength of the hydrophobic interactions between the hydrocarbon chains of fatty acids and the strength of the hydrophobic interactions is actually what effects the melting point of the fatty acids. And so these two factors, by affecting the strength of the hydrophobic interactions there, are also affecting the melting point of the fatty acids. And so the first of these two primary factors is going to be the length of the hydrocarbon chains or the amount of carbon atoms that are present in the hydrocarbon chains. And so the longer these hydrocarbon chains are, the higher the melting point will actually be. And so, if we take a look down below at our image at Table number one, which corresponds with number one up above, you'll notice that we have the fatty acid name in the first column, and the second column practically has the number of carbon atoms or the length of the hydrocarbon chain. And the third column has the corresponding melting point in degrees Celsius, and you'll notice that as we increase the number of carbon atoms in the hydrocarbon chain. Or as we increase the length of the hydrocarbon chain, the melting point is also increasing. And so it's true that the longer the chain is, the higher the melting point will be. Now. The second primary factor that effects the strength of hydrophobic interactions, and thus the melting point of the fatty acids, is going to be the degree of saturation of the hydrocarbon chains or the amount of double bonds that are present in the hydrocarbon chain. And so this time it turns out that the MAWR double bonds there are in the hydrocarbon chain, the lower the melting point is going to be. And so if we take a look at our second table table number two, which corresponds with number two up above notice again, we have the fatty acid chain name in the first column, and then we have the degree of saturation, or the number of double bonds in the second column and again the melting point and degrees Celsius in the third column. And notice that this time as we increase the number of double bonds, that the melting point is actually decreasing and so we start off with positive 16 degrees and we go down to negative degrees. So the melting point temperature is actually decreasing as we increase the number of double bonds. Just like what we set up above the mawr double bonds, the lower the melting point. And so therefore because this here is true, this means that unsaturated fatty acids, which are gonna end up having kinks in their chain due to the double bonds, are gonna also end up having lower melting points than saturated fatty acids. And so, if we take a look at our image over here, which will note is on the left hand side. We have saturated fatty acids. And on the right hand side, what we have are unsaturated fatty acids. And so taking a look at the saturated fatty acids over here on the left hand side notice that they are pretty highly packed. And that's because they don't have any double bonds and they don't have any kinks in their chain. And so they're fatty acid. Chains are able to be pretty linear, and they're able to be pretty highly packed and they're so highly packed, the more packing there is the more hydrophobic interactions that conform between all of these hydrophobic chains. And the more hydrophobic interactions there are, the higher the melting point will be. Now, on the other hand, taking a look at the unsaturated fatty acids which again are gonna have these double bonds. The double bonds are ultimately going to create kinks in the chains of these unsaturated fatty acids. And so notice that these chains are not linear, they're actually forming these kinks, and that makes them, ah, lot harder to pack tightly. So they are going to be less packed. And if they're less packed, that means that they're going to be less hydrophobic. Interactions forming between them and less hydrophobic interactions corresponds with having a lower melting point. Now, ah, higher melting point means that at room temperature, these are are going to be solids at room temperature such as butter, which are against solids at room temperature. And on the other hand, having a lower melting point means that you're gonna melt a lot easier at room temperature. And so they're going to be liquids at room temperature such as oils and so down below. We've defined fats as a general term referring to um lipids, or fatty acids, that air solids at room temperature. And then, of course, oils are going to be liquids at room temperature on which will notice is that the fats, such as butter, here they're typically extracted from animals. And that's because although animals have both saturated and unsaturated fatty acids, they tend to have a higher percentage of saturated fatty acids. And so fats are typically extracted from animals and, on the other hand, plants on oils. I'm sorry oils, which are liquids at room temperature. They tend to be extracted from plants, and that's because plants again. Although they have both saturated and unsaturated fatty acids, they tend to have a higher percentage of unsaturated fatty acids. And that's what allows oils to be extracted from plants typically. And so this year concludes our lesson on the melting points of fatty acids, and we'll be able to get some practice applying all of these concepts in our next couple of practice problems. So I'll see you guys there
6
Problem
Problem
What aspect of each of the 18-carbon fatty acids in the table below is correlated with their melting point?
a) The charge of the carboxylic acid group.
b) The length of the hydrocarbon chain
c) The number of double bonds
d)The polar hydrocarbon chains
A
The charge of the carboxylic acid group.
B
The length of the hydrocarbon chain
C
The number of double bonds
D
The polar hydrocarbon chains
7
Problem
Problem
What happens to the melting point in fatty acids as the hydrocarbon length increases?
a) It increases.
b) It decreases.
c) It stays the same.
d) There is no direct correlation.
A
It increases.
B
It decreases.
C
It stays the same.
D
There is no direct correlation.
8
Problem
Problem
Unsaturated fatty acids:
a) Usually contain a double bond with cis stereochemistry.
b) Are found in both plants and animals.
c) Sometimes contain multiple double bonds.
d) Have lower melting points than the analogous saturated fatty acids.
e) All of the above are correct.
A
Usually contain a double bond with cis stereochemistry.
B
Are found in both plants and animals.
C
Sometimes contain multiple double bonds.
D
Have lower melting points than the analogous saturated fatty acids.
E
All of the above are correct.
9
Problem
Problem
Which of the following are correct with regard to saturated fatty acids?
a) They are generally solid at room temperature.
b) The carbon backbone contains at least one double bond, creating a kink in the chain.
c) Come primarily from vegetable products.
d) They are only hydrocarbon chains, making them liquids at room temperature.
e) Cannot be present in other lipids, such as phospholipids.
A
They are generally solid at room temperature.
B
The carbon backbone contains at least one double bond, creating a kink in the chain.
C
Come primarily from vegetable products.
D
They are only hydrocarbon chains, making them liquids at room temperature.
E
Cannot be present in other lipids, such as phospholipids.
10
Problem
Problem
Match each of the fatty acids with the appropriate melting point:
