While each product featured is independently selected by our editors, we may include paid promotion. If you buy something through our links, we may earn commission. Read more about our Product Review ...

The defining feature of an amino acid is its side chain (at top, blue circle; below, all colored circles). When connected together by a series of peptide bonds, amino acids form a polypeptide, another ...

Proteins are made of amino acid chains, or polypeptides. Amino acids have a basic backbone made of an amino group and a carboxyl group, and differ in their side-chains. These polypeptide chains of ...