In this video, we're going to begin our lesson on proteins. Now, proteins are one of the major classes of biomolecule polymers that are made up of amino acid monomers. Amino acids are the monomers that make up proteins. The covalent bonds that link adjacent amino acids together in a chain are specifically referred to as peptide bonds. We'll be able to see some examples of these peptide bonds down below in our image.

But, it's also important to note that protein polymers have directionality, meaning that in the chain of the protein polymer, one end is chemically different from the opposite end. These ends are referred to as the N-terminal end and the C-terminal end. Let's take a look at our example image down below showing the formation of proteins from amino acid monomers to get a better idea of these concepts. Notice on the far left-hand side we are showing you all of these separate individual circles which represent amino acid monomers. These amino acids are separate from each other.

Of course, if we join these amino acid monomers together in a chain like what we see here, we're building ourselves a protein polymer. Notice that the protein polymer has directionality because on one end, it's chemically different from the opposite end. The end that has the amino group, like what we see over here, is referred to as the N-terminal end because the amino group has a nitrogen atom. This other group that we see over here on the opposite end is referred to as the C-terminal end because it has a carboxyl group, which we see here. Notice that each of these separate amino acid monomers is being covalently linked together through these bonds that we see right here, and these bonds that covalently link the adjacent amino acids together are referred to as peptide bonds.

This here really concludes our introduction to proteins, and we're going to continue to talk more and more about proteins as we move forward in our course. I'll see you all in our next video.