In Some Cases, a Single Amino Acid Substitution Can Cause

question 155

Multiple Choice

In some cases, a single amino acid substitution can cause a protein to lose its biological activity.In other cases, a single amino acid substitution causes no change to a protein's biological activity.Which statement can best be used as evidence to support an explanation for these observations?

• A) Amino acids are covalently linked through peptide bonds to form the primary structure of a protein.
• B) Amino acids found in the proteins of living organisms have many similarities, including an alpha-amino group and an alpha-carboxyl group.
• C) Amino acids occur as optical isomers, but only one isomer of each is found in the proteins of most of the organisms on Earth.
• D) Noncovalent interactions between atoms in a polypeptide chain stabilize the secondary, tertiary, and quaternary levels of its structure.
• E) Each amino acid side chain has properties that are very different from those of some side chains and very similar to those of others.

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