Functional groups are specific groups of atoms or bonds within a molecule that are responsible for the characteristic chemical reactions of that molecule. They are used to distinguish similar compounds from each other and can be added to a compound to afford it new, desirable properties. Functional groups are responsible for the distinctive chemical reactions of molecules and play a significant role in forming biological molecules such as DNA, proteins, carbohydrates, and lipids. Some of the essential functional groups in biological molecules include hydroxyl, methyl, carbonyl, carboxyl, amino, phosphate, and sulfhydryl groups. Examples of functional groups include alcohol, aldehyde, ketone, and more. In organic chemistry, functional groups are specific groups of atoms or bonds that give a compound certain physical and chemical properties.