In this video, we take a look at our polar amino acids. Now here, they contain our groups that are polar and therefore hydrophilic. When we say hydrophilic, it means water-loving, and therefore interacts with water. We're going to say all except cysteine form hydrogen bonds with water. And the memory tool that we can utilize to remember which ones are classified as polar amino acids is that Santa's team tirelessly crafts new quilts. So here we have our first letters as well as TYR tirelessly to help us remember our amino acids here. So, Santa stands for serine, which is SER and S. Serine here has a CH2OH as its R group. The presence of that OH group, we know that it can form hydrogen bonds with water.
Next, we have threonine, which is going to be THR and then T. It too also has an OH group. And that OH group is then going to be overpowered by an abundance of carbons within this R group. There's only 2 other carbons within this R group. Then we have Tyrosine here, TYR, Tyrosly. Here, Tyrosine is phonetic in origin, so it's Y. This one is larger; it's a CH2 group connected to Benzene connected to an OH group. We can see a theme developing here for these first three. All of them have OH groups on their R group.
Then we have here is cysteine, which is unique because here it is a thiol. Remember a thiol is an SH group. So CH2SH forms its R group here. Its 3 letter code would be CYS, and then here it is unique that it's the only of the 20 amino acids that begins with C. Asparagine, remember this is phonetic in origin, so it'd be ASN, and then N. Here we have an amide group to complete the last two of these amino acids.
Let's talk about glutamine as well, so GLN and then Q. This is also phonetic in origin. Both of these have this nitrogen here, an amide end. The difference between them is that asparagine only has 1 CH2 connected to it, but then glutamine is a little bit bigger, so it has 2 CH2 groups connected to that amide group.
So this is a way of looking at their similarities and their slight differences from one another. So remember, these are classified as all the polar amino acids out of the 20 that you need to remember. And the memory tool you can utilize here is that Santa's team tirelessly crafts new quilts. Okay? So just remember that memory tool to help you organize these different types of polar amino acids.