Which term is used to describe molecules that are the building blocks of proteins?

Molecules that serve as the building blocks of proteins are called amino acids. Each amino acid consists of a central carbon atom, an amino group, a carboxyl group, a hydrogen atom, and a specific side chain or R group that distinguishes one amino acid from another. Proteins are formed when amino acids bond together through peptide bonds in a specific sequence, determining the protein's structure and function. There are 20 different standard amino acids, and the sequence and arrangement of these amino acids in proteins are crucial for the diversity of protein functions in living organisms.

Other options refer to different types of biomolecules: nucleotides are the building blocks of nucleic acids like DNA and RNA, sugars are the building blocks of carbohydrates, and fatty acids are components of lipids. Each of these plays a distinct role in biological systems, separate from the role that amino acids play in protein synthesis.