Protein

A protein is a large complex molecule made up of one or more chains of amino acids. Proteins perform a wide variety of activities in the cell.

Amino acids are a group of 20 different kinds of small molecules that link together in long chains to form proteins. Often referred to as the "building blocks" of proteins.

Sources:  image from the National Human Genome Research Institute (NHGRI) Genetic Illustrations; definitions from the National Human Genome Research Institute (NHGRI) Glossary of Genetic Terms