Even the best of microscopes are incapable of revealing the details of atoms, molecules, or even macromolecules, much less the details of chemical reactions. Such knowledge comes from the investigations of countless scientists (chemists) interpreting the results of literally millions of experiments. The chemistry of what goes on in living things is BIOCHEMISTRY.
Analyzing what living things are made of has revealed four just four basic kinds of very large molecules, i.e., MACROMOLECULES (smaller ones aside).
proteins (see below)
nucleic acids (DNA, RNA, Lesson B-27)
carbohydrates (starch, sugars, cellulose in plants (Lesson B-23)
lipids (fats and oils)
Proteins are most significant. In both animals and plants, proteins are the ENZYMES, which control all chemical reactions occurring in all cells of all living organisms. Therefore, we wish to understand their nature in more detail. (In animals proteins are also the major component of muscle, skin, hair, nails, and certain other tissues.