 Proteins ( / <unk> / or / <unk> / ) are large biomolecules , or macromolecules , consisting of one or more long chains of amino acid residues . Proteins perform a vast array of functions within organisms , including <unk> metabolic reactions , DNA replication , responding to <unk> , and transporting molecules from one location to another . Proteins differ from one another primarily in their sequence of amino acids , which is dictated by the nucleotide sequence of their genes , and which usually results in protein folding into a specific three @-@ dimensional structure that determines its activity . 
