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.

• 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 levels of protein structure: primary, secondary, tertiary, and quaternary. Each level has distinct characteristics and interactions.
2. Recall that peptide bonds are formed through a dehydration synthesis reaction, not hydrolysis. Hydrolysis breaks bonds, while dehydration synthesis forms them.
3. Recognize that peptide bonds connect the carboxyl group of one amino acid to the amine group of another, not the R group. The R group is involved in tertiary structure interactions.
4. Identify that secondary protein structures, such as alpha helices and beta sheets, are stabilized by hydrogen bonds between the backbone atoms (N-H and C=O) of the polypeptide chain.
5. Clarify that tertiary protein structure refers to the overall 3D shape of a single polypeptide chain, stabilized by interactions among R groups, while quaternary structure involves multiple polypeptide chains.