Which of the Following Statements About Protein Structure is Correct

Question

Which of the following statements about protein structure is correct?
A) The primary structure of a protein does not dictate the final shape of the protein.
B) Two common types of secondary structure are a helices and b sheets, both of which are held in place via hydrogen bonds.
C) Tertiary protein structure is maintained primarily by covalent disulfide bridges.
D) All peptides exhibit four levels of structural organization: primary, secondary, tertiary, and quaternary.
E) Ionic bonds in tertiary structure maintain a strong attraction between amino acids in the interior of living cells.

Accepted Answer

The two common types of secondary structure in proteins are alpha-helices and beta-sheets, which are stabilized by hydrogen bonds between amino acids. The primary structure of a protein does, in fact, dictate the final shape of the protein, and tertiary structure is primarily maintained by non-covalent interactions (such as hydrogen bonds, hydrophobic interactions, and ionic bonds), not by covalent disulfide bridges. Also, not all peptides exhibit quaternary structure. Finally, ionic bonds can maintain strong attractions between amino acids, but they are not the only non-covalent interactions involved in tertiary structure.