What are the building blocks of proteins known as?

The building blocks of proteins are known as amino acids. These organic compounds consist of a basic structure that includes an amino group, a carboxyl group, and a unique side chain, which varies among different amino acids. There are 20 standard amino acids that combine in various sequences to form proteins, playing critical roles in biological functions, including enzymes, antibodies, and structural components of cells.

The significance of amino acids lies in their ability to join together through peptide bonds, forming polypeptides, which fold into specific three-dimensional shapes to create functional proteins. Each protein's unique sequence and composition of its constituent amino acids largely determine its structure and function in the body.

Other options such as fatty acids, nucleotides, and sugars represent different classes of biological molecules. Fatty acids are primarily components of lipids, nucleotides are the building blocks of nucleic acids like DNA and RNA, and sugars are carbohydrates. While each of these plays essential roles in cellular processes, they are not involved in the formation of proteins. Thus, amino acids are specifically recognized as the fundamental units that make up proteins.