Fatty acids are not formed by dehydration reactions, but DNA, protein, amylase, and disaccharides are formed by dehydration reactions. Dehydration can be expressed as a condensation reaction. It refers to a conversion that has to do with the water loss from the reacting ion or molecule.
Dehydration reactions often show up in chemistry, and it is the inverse of hydration reaction. The major factor that affects dehydration reactions most of the time is the heat factor. During this reaction, an unsaturated compound is formed, and this happens when a water molecule is being removed from the combination of two compounds.
The items listed above are actually parts of the biomolecule groups, but fatty acid monomers are not bonded to each other directly in polymer chains. The reactions of dehydration synthesis on lipids lead to the formation of an ester linkage between the hydroxyl group of an alcohol monomer and the carboxyl group of a fatty acid.