Final answer:
The true statement about the secondary structure of a protein is that it involves the folding of the polypeptide into an organized and predictable pattern, which is option b. This folding, including formations like alpha-helix and beta-pleated sheet, is maintained by hydrogen bonds between the amino acids in the chain.
Step-by-step explanation:
The secondary structure of a protein refers to the localized folding of the polypeptide chain into regular structures like the alpha-helix and beta-pleated sheet. These configurations are maintained by hydrogen bonds that form between the oxygen atom in the carbonyl group of one amino acid and the amino group of another amino acid that is four residues further along the chain. This structure is an organized and predictable pattern resulting from the chemical properties of the polypeptide backbone and its local interactions.
Considering the options provided:
- a. This statement is incorrect. The joining of two or more polypeptide chains relates to the quaternary structure of a protein.
- b. This statement is correct. It involves the folding of the polypeptide into an organized and predictable pattern.
- c. This statement is incorrect for secondary structure. The genetic code determines the primary structure of the protein, which is the sequence of amino acids.
- d. This statement is incorrect. The basic chemical and physical characteristics of proteins are more directly determined by their primary structure, although all levels of structure do contribute to a protein's properties.