What are proteins primarily made of?

Proteins are primarily made of amino acids, which are organic compounds that contain both an amino group and a carboxyl group. Amino acids are the building blocks of proteins, and they link together through peptide bonds to form long chains that fold into specific shapes, determining the protein's function. There are 20 different amino acids that combine in various sequences to produce a vast array of proteins needed for different biological functions such as enzyme catalysis, support, transport, and signaling within living organisms.

Other options like fatty acids, carbohydrates, and nucleotides are not the fundamental components of proteins. Fatty acids are the building blocks of lipids, carbohydrates consist of sugar molecules, and nucleotides are the building blocks of nucleic acids like DNA and RNA. Understanding the unique role of amino acids in the structure and function of proteins is essential in the field of biochemistry and biology.