Which organic compounds are comprised of both an amino group and a carboxylic acid group?

Amino acids are the organic compounds that contain both an amino group (-NH2) and a carboxylic acid group (-COOH). These functional groups are crucial for the structure and function of amino acids. The amino group contributes to the basic properties of amino acids, while the carboxylic acid group gives them acidic characteristics.

In the context of proteins, amino acids serve as the building blocks. When amino acids link together through peptide bonds, they form polypeptides, which can further fold into functional proteins. However, polypeptides themselves do not represent the basic structure that includes both the amino and carboxylic acid groups.

Lipids are a separate class of organic compounds that are primarily hydrophobic and are not characterized by the presence of both an amino and a carboxylic acid group.

Polymers refer to larger molecules made up of repeating subunits, which can include proteins formed from linked amino acids but do not specifically denote the presence of the amino and carboxylic acid groups.

Thus, the defining characteristic of amino acids, with their dual functional groups, makes them the suitable choice for this question.