Which end of the fatty acid molecule is characterized as nonpolar and water-fearing?

The end of the fatty acid molecule that is characterized as nonpolar and water-fearing is indeed described as hydrophobic. Fatty acids consist of long hydrocarbon chains that lack affinity for water due to their nonpolar nature, making them hydrophobic. This means they do not readily mix with water and are instead repelled by it.

In the context of fatty acids, the hydrophobic properties are significant because they influence how these molecules interact in biological systems. For example, in an aqueous environment, fatty acids tend to aggregate with one another, a behavior that contributes to the formation of cell membranes and lipid bilayers. This ability to form structures that exclude water is essential for the formation of protective barriers in cells.

The other terms such as hydrophilic, which refers to water-attracting properties, and amphipathic, which describes molecules that contain both hydrophobic and hydrophilic parts, apply to different aspects of molecular interactions but do not accurately characterize the nonpolar, water-fearing end of a fatty acid. Additionally, carbonyl refers to a specific functional group that contains carbon and oxygen; while it is present in some fatty acids, it does not represent the overall hydrophobic nature of the fatty acid molecule.