What functional group characterizes carboxylic acids?

Carboxylic acids are characterized by the presence of the carboxyl group, which is represented as COOH. This functional group consists of a carbon atom that is doubly bonded to an oxygen atom (the carbonyl part) and also bonded to a hydroxyl group (the -OH part). The combination of these two components imbues carboxylic acids with their distinctive properties, including their ability to donate protons (H+) in aqueous solutions, making them acidic in nature.

The presence of this carboxyl group is crucial for the reactivity and behavior of carboxylic acids in various biochemical processes. Carboxylic acids play a vital role in metabolism and are involved in the synthesis of lipids and amino acids, as well as functioning as intermediates in various metabolic pathways.

In contrast, other functional groups mentioned, such as the carbonyl group and hydroxyl group, are parts of different functional groups (ketones and alcohols, respectively) that do not impart the same properties as a carboxylic acid. The amino group, consisting of nitrogen, is characteristic of amino acids, not carboxylic acids. Thus, the carboxyl group is the defining feature of carboxylic acids,