Question

which molecule is the building block of a protein? monosaccharide glycerol disaccharide phosphate group fatty acid amino acid

Explanation:

Proteins are polymers made up of amino - acid monomers. Monosaccharides and disaccharides are related to carbohydrates. Glycerol and fatty acids are parts of lipids. Phosphate groups are components of nucleic acids and some lipids.

Answer:

amino acid