Proteins are primarily made up of what building blocks?

Proteins are primarily made up of amino acids, which are organic compounds composed of an amino group, a carboxyl group, and a unique side chain or R group. These amino acids link together through peptide bonds to form long chains, ultimately folding into complex structures that determine the function of the protein in biological processes.

Each protein is made up of a specific sequence of amino acids, which is dictated by the genetic code within an organism's DNA. This sequence and the chemical properties of the amino acids influence how the protein folds and its ultimate role in the body, such as catalyzing reactions, providing structural support, or facilitating communication between cells.

The other options represent different categories of biological molecules: nucleotides are the building blocks of nucleic acids (like DNA and RNA), fatty acids are components of lipids (fats), and monosaccharides are the simplest form of carbohydrates, typically used for energy. Each of these plays important roles in biology, but they do not contribute to the formation of proteins.