A biomolecule with a hydroxyl (--oh) functional group is given the polar chemical property since organic molecules with an OH group are polar.
A part of a larger molecule is made up by a functional group. The hydroxyl group (-OH) that characterizes alcohols, an oxygen with a hydrogen attached, is an example of it. This group can be found on any number of different molecules.
Functional groups have characteristic chemistries, just as elements have unique properties., although perhaps not identically, to an -OH on another molecule. Although perhaps not identically to an -OH on another molecule, an -OH group on one molecule will tend to react similarly.