Question

the model below shows parts of the primary and secondary structures of a protein. select the true statement. a primary structure forms when a secondary structure folds into a shape. the types of amino acids in a polypeptide determine the shape of its secondary structures. all proteins have the same secondary structures.

Explanation:

• Option A: The primary structure is the linear sequence of amino acids. The secondary structure (like alpha - helix and beta - sheet) forms from the primary structure due to hydrogen bonding, not the other way around. So, this option is false.
• Option B: The types of amino acids in a polypeptide chain influence the formation of secondary structures. For example, proline often disrupts alpha - helices. The sequence of amino acids (primary structure) dictates how the polypeptide will fold into secondary structures (through hydrogen bonding). So, this option is true.
• Option C: Not all proteins have the same secondary structures. Different proteins have different combinations of alpha - helices, beta - sheets, or may have only one type or even no regular secondary structures in some regions. So, this option is false.

Answer:

B. The types of amino acids in a polypeptide determine the shape of its secondary structures.