Your body contains tens of thousands of different proteins, each with a specific structure and function. the unique three-dimensional shape of each of these diverse proteins is based on several superimposed levels of structure. which of the following statements is/are accurate descriptions of proteins? select all that are correct. a. the primary structure of a protein is the order of amino acids in a polypeptide, as coded for in the dna of a gene. b. the 20 amino acids found in proteins differ in the composition of their r groups. c. secondary structures, which include the alpha helix or beta pleated sheet, are held together by ionic bonds between r groups. d. tertiary structure is the overall shape of a polypeptide, which may be stabilized by hydrophobic interactions and ionic bonds. e. quaternary structure is only found in proteins that have more than one polypeptide subunit