What is the compound name for a molecule that includes a methyl group?

A methyl group consists of one carbon atom bonded to three hydrogen atoms, represented chemically as -CH₃. When a molecule includes a methyl group, it is often referred to as a "methylated compound." This term indicates that the molecule has undergone a reaction where a methyl group has been added to it, modifying its structure and potentially its biological activity.

This specificity is important in biological systems, as the addition of a methyl group can influence a molecule's reactivity, solubility, and interaction with other molecules. Methylation is a common biochemical modification in processes such as DNA methylation, which can affect gene expression.

The other options refer to different functional groups that are not related to the presence of a methyl group. Hydroxyl compounds contain -OH groups, amino compounds contain -NH₂ groups, and carboxyl compounds contain -COOH groups. Each of these functional groups imparts distinct properties to molecules but does not include the methyl group itself.