What type of compound is formed when a methyl group is added to a molecule?

When a methyl group is added to a molecule, the resulting compound is referred to as a methylated compound. Methylation is a common process in organic chemistry and biochemistry that can significantly modify the properties and reactivity of the original molecule. This addition often affects the biological activity, solubility, and stability of the molecules involved.

For instance, the methylation of DNA can influence gene expression and is a key mechanism in epigenetics. Methylated compounds can have varying hydrophobic or hydrophilic characteristics, but the term "methylated" specifically denotes the presence of a methyl group within the structure of the compound.

Understanding this principle is essential in biology and chemistry, as the methylation of compounds plays a critical role in metabolic processes and interactions within biological systems.