Separating Biomolecules In studying a particular biomolecule (a protein, nucleic acid, carbohy- drate, or lipid) in the laboratory, the biochemist first needs to separate it from other biomolecules in the sample that is, to purify it. Specific purification techniques are described later in the text. How- ever, by looking at the monomeric subunits of a biomolecule, you should have some ideas about the characteristics of the molecule that would allow you to separate it from other molecules. For example, how would you separate (a) amino acids from fatty acids and (b) nucleotides from glucose?