Proteins are digested to simpler substances. What are these simpler substances called?

• A. Amino acids
• B. Peptides
• C. Nucleotides
• D. Monosaccharides

Answer: (A)

Proteins are polymers made of amino acids linked by peptide bonds, and digestion uses proteases to break those bonds. As digestion proceeds, the proteins are chopped down through shorter peptides and then into the smallest building blocks: amino acids. These amino acids are what the body absorbs to use for making new proteins and other molecules. Peptides are intermediate products along the way, but they’re not the final, simplest substances. Nucleotides come from nucleic acids, and monosaccharides come from carbohydrates, so they aren’t the products of protein digestion.