Which macromolecule is formed from a glycerol backbone with three fatty acids?

• A. Proteins
• B. Nucleic Acids
• C. Carbohydrates
• D. Lipids

Answer: (A)

This structure is a lipid, specifically a triglyceride. A glycerol backbone linked to three fatty acids forms ester bonds with each fatty acid, producing a triacylglycerol. Lipids are distinct from proteins, nucleic acids, and carbohydrates because they’re not built from repeating monomers like amino acids, nucleotides, or sugar units; instead, triglycerides combine glycerol and fatty acids to create a highly nonpolar, energy-dense molecule. Proteins are made from amino acids, nucleic acids from nucleotides, and carbohydrates from sugar units, none of which match the glycerol-plus-three-fatty-acid architecture.