I would focus on functional groups, especially those seen in biomolecules. They include amides, acetals, and, carboxylic esters, phosphodiesters, to name four important ones that come from the four major classes of biological macromolecules. Knowing the rudiments of kinetics never hurt anyone, either. There are also a couple of books that are intended to help students see the forest from the trees" Gilbert's "Basic concepts in biochemistry" and "PDQ Biochemistry" by Baker and Murray.