The tertiary structure of a protein is the A) bonding together of several polypeptide chains by weak bonds. B) order in which amino acids are joined in a polypeptide chain. C) unique three-dimensional shape of the fully folded polypeptide. D) organization of a polypeptide chain into an ? helix or ? pleated sheet. E) overall protein structure resulting from the aggregation of two or more polypeptide subunits.