Which option lists the monomer type of proteins?

• A. Nucleotides
• B. Amino acids
• C. Simple sugars
• D. Fatty acids

Answer: (B)

Proteins are made by linking smaller units called amino acids into long chains. Each amino acid has an amino group, a carboxyl group, and a side chain (the R group) that gives it unique properties. When two amino acids join, the carboxyl group of one forms a peptide bond with the amino group of the next, releasing a molecule of water. Repeating this linkage creates a polypeptide that folds into a functional protein.

That’s why amino acids are the monomer type for proteins. Nucleotides are the building blocks of nucleic acids (DNA, RNA); simple sugars are the monomers of carbohydrates; and fatty acids are components of lipids.