Which of the following is true of protein structure?

• A. Peptide bonds are formed by hydrolysis.
• B. Peptide bonds join the amine group on one amino acid with the R group of another amino acid.
• C. Secondary protein structures are caused by hydrogen bonding between atoms of the peptide backbone.
• D. Tertiary protein structure emerges when there is more than one polypeptide in a protein.

Answer: (C)

Verified step by step guidance

1. Understand the basic structure of proteins, which are composed of amino acids linked together by peptide bonds. These bonds form between the carboxyl group of one amino acid and the amine group of another, releasing a molecule of water in a dehydration synthesis reaction.
2. Recognize that peptide bonds are not formed by hydrolysis. Hydrolysis is the process of breaking down molecules by adding water, which is the opposite of how peptide bonds are formed.
3. Identify that peptide bonds do not join the amine group of one amino acid with the R group of another. Instead, they connect the carboxyl group of one amino acid to the amine group of the next.
4. Learn about secondary protein structures, which are formed by hydrogen bonds between the atoms of the peptide backbone. These structures include alpha helices and beta-pleated sheets.
5. Clarify that tertiary protein structure refers to the overall three-dimensional shape of a single polypeptide chain, stabilized by various interactions, including hydrogen bonds, ionic bonds, and disulfide bridges. It does not require more than one polypeptide chain; that would be quaternary structure.