The four main types of macromolecules in biological systems are proteins, nucleic acids, carbohydrates, and lipids. Each of these macromolecules plays distinct roles; proteins serve as enzymes and structural components, nucleic acids store genetic information, carbohydrates provide energy and structural support, and lipids function in energy storage and cell membrane formation. Understanding these macromolecules is fundamental to biochemistry and molecular biology, as they are essential for life processes.