The chains of smaller molecules that make up proteins are called amino acids.

Here's a bit more detail:

* Amino acids are the building blocks of proteins. They are organic molecules that contain an amino group (-NH2), a carboxyl group (-COOH), and a side chain (R group) that is unique to each amino acid.

* These amino acids are linked together by peptide bonds, which are formed through a dehydration reaction.

* A chain of amino acids linked together by peptide bonds is called a polypeptide.

* A protein is one or more polypeptide chains that have folded into a specific three-dimensional structure.

So, to sum it up, proteins are made up of chains of amino acids, which are connected by peptide bonds to form polypeptide chains. These polypeptide chains then fold into specific structures to create a functional protein.