In this video, we're going to talk some more details about amino acids. Now amino acids, recall from our last lesson video, are really just the monomers of proteins. And so linking together multiple amino acids allows us to build a protein polymer. Now each individual amino acid monomer is going to contain common components that are common to all amino acids, and then they're also going to contain some unique components such as the unique R group. And we'll be able to see the common components and the unique R group down below once we get to our image.
But living organisms primarily use a total of 20 different amino acids. And once again, these different amino acids, they all have common components that we're going to talk about, but each of the 20 amino acids also has a unique R group. So let's take a look at our example down below to get a better understanding of these ideas. We're taking a look at the amino acid structure. And over here on the left, what we have is a table of the amino acid components.
Recall in our last lesson video, we were representing amino acids using these circles. And so, these circles, each of these circles has these components that we're talking about, and these components you can see over here in a more detailed chemical structure of the amino acid. Each of these amino acids is going to have common components which we have in the red box. So the red dotted box that you see here represents the common components that are found in all twenty of the different amino acids. And, down below what you'll see is a green shading which is going to be the unique region of the amino acid that will differ between all of these 20 amino acids.
When we look at the common components, notice that it starts with the central carbon atom which is also known as the alpha carbon. And so over here when we look at the chemical structure you can see that the central carbon atom is right here in the center, right in the middle. Now coming up off the top of the central carbon atom, we have a central hydrogen atom. So that would be this, hydrogen atom that we see here. And again, this is a common component found in all amino acids.
And then going to the left and going to the right of the central carbon atom, we have these 2 functional groups that you should recognize. Going to the left over here in blue, what we have is an amino group which is where the N-terminal end would be for this amino acid. And then of course going to the right over here in yellow, what we have is a carboxyl group which is going to be the C-terminal end of the amino acid. And so once again, all of these components that we talked about here are the common components found in every single amino acid. And really what makes one amino acid different from another amino acid is going to be the R group, the unique R group.
And so we can put the R group here, and the R group you can pretty much think that the R stands for the R in the rest of the molecule because the R group is going to be variable. It will change from amino acid to amino acid and it represents the rest of the molecule. Some amino acids have a really small R group with just a handful of atoms, just maybe one atom sometimes. Other amino acids have R groups that are much larger in size and have many more atoms and they're much more complicated. But the backbone, this region here is going to be common for all amino acids.
So that's important to keep in mind. Now for your biology class, you're likely not going to need to know all 20 of the different amino acids but you will need to know that there are 20. And you will need to know the common components and the fact that they all have a unique R group that has different properties. And so this here concludes our introduction to amino acids and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you guys in our next video.