What molecules make up the human body?
All cells contain all four types of macromolecules. Actually, it would not surprise me if there are exceptions to this, but I cannot think of any. The composition of different cells differs. Adipocytes (fat cells), for example, contain mostly triacylgycerols (triglycerides) but they also have proteins, carbohydrates and nucleic acids. Erythrocytes (red blood cells) lack a nucleus so they do not have as much nucleic acid as other cell types in the same organism, but they do have mitochondrial DNA. Many proteins serve a strictly structural role, but arguably the most important function of proteins is their role as enzymes which catalyze (speed up the rate of) biochemical reactions. Proteins really do most of the work of a cell: they transport things, they take apart and build things, they are involved in cell growth and movement. Without proteins, cells would not be able to do work and would basically be stuck passively responding to their environment. In a multicellular organism like a
