What type of macromolecule is insulin?

Insulin is classified as a protein because it is composed of long chains of amino acids that are folded into a specific three-dimensional shape. Proteins are one of the four major types of macromolecules and perform a variety of functions in the body, including acting as enzymes, hormones, and structural components of cells.

Insulin specifically functions as a hormone that regulates glucose levels in the blood, highlighting its role in metabolism and homeostasis. Its structure consists of two polypeptide chains linked by disulfide bonds, which is characteristic of many proteins. The presence of these amino acid chains and their unique folding are key factors that define insulin’s activity and functionality in biological processes.

In contrast, lipids are primarily composed of fatty acids and do not form long chains of amino acids. Carbohydrates are made up of sugar molecules and serve different functions, such as providing energy. Nucleic acids, like DNA and RNA, have a distinct structure involving nucleotides and are responsible for genetic information storage and transmission. Thus, insulin's definition and functionality as a protein is clear within the context of these macromolecule classifications.