Proteins are composed of folded chains of molecules called amino acids.

Let's break down why:

* Proteins: These are large, complex molecules that perform a vast array of functions in living organisms.

* Amino acids: These are the building blocks of proteins. There are 20 different types of amino acids commonly found in proteins.

* Folded chains: The amino acids link together to form long chains. These chains then fold into specific three-dimensional shapes, which are crucial for the protein's function.

Let me know if you have any other questions!