Amino acids are characterized by their central carbon atom, known as the α-carbon, which is bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable side chain ...

Each of the 20 amino acids has a specific side chain, known as an R group, that is also attached to the α carbon. The R groups have a variety of shapes, sizes, charges, and reactivities.

Within a protein, multiple amino acids are linked together by peptide bonds, thereby forming a long chain. Peptide bonds are formed by a biochemical reaction that extracts a water molecule as it ...

The sequence of amino acids in the chain determines how the chain will fold up to make the protein, so different proteins have different three-dimensional shapes. The three-dimensional shape of a ...