Macromolecules are the most interesting and characteristic molecules of living systems; in a true sense, the evolution of life as we know is the evolution of macromolecular structures.
Proteins, the workhorses of the cell are the most abundant and functionally versatile of the cellular macromolecules.
Living beings are like factories, which need easily available raw materials. Just as factories need machines, the machines of living organisms are specific protein molecules called enzymes. Enzymes cause chemical changes to convert food into body parts such as tissues, the muscle etc. All this doesn’t happen in a single step, but along an assembly line called "metabolic pathway".
Our energy is obtained by burning fuel. The three major constituents of our food namely carbohydrates, fats and proteins function as fuels, as well as provide raw materials for building our tissues.
To understand life, we need to know about the chemical properties and reactions of the organic compounds that make us. DNA provides the molecular basis of the template needed for genetic replications. With this discovery, the field of molecular biology was born − the field essentially owes its origin to chemical basis of life.