What are proteins composed of?

Proteins are fundamentally composed of chains of amino acids. These amino acids are organic compounds that serve as the building blocks of proteins, each containing an amino group, a carboxyl group, and a unique side chain or R group that determines the amino acid's properties. The sequence and arrangement of these amino acids determine the protein's structure and function, which can vary greatly depending on the specific combination and sequence.

During the process of protein synthesis, amino acids are linked together by peptide bonds in a specific order dictated by the genetic code. This polypeptide chain then folds into a three-dimensional structure that is critical for the protein's biological activity. The diverse range of functions performed by proteins—such as acting as enzymes, hormones, structural components, and antibodies—arises from their unique sequences of amino acids and the resulting complex shapes they adopt.

This distinction is crucial because other biological macromolecules serve different roles. For example, nucleotides form nucleic acids like DNA and RNA, monosaccharides are the building blocks of carbohydrates, and fatty acids are components of lipids. Understanding that proteins are specifically formed from amino acids is essential for grasping broader biological concepts, including metabolism, genetics, and cellular physiology.