The side chain of an amino acid determines where a protein _

The building blocks of proteins are amino acids, which are small organic molecules that consist of an alpha (central) carbon atom linked to an amino group, a carboxyl group, a hydrogen atom, and a variable component called a side chain (see below). ... Theside chains of amino acids have different chemistries.

The side chain of an amino acid, the r group, determines where a protein is located and what it specifically helps with.