A chain of amino acids linked by peptide bonds forms what biomolecule?

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

Answer: (D)

A chain of amino acids linked by peptide bonds forms proteins. Peptide bonds arise when the amino group of one amino acid bonds to the carboxyl group of the next amino acid in a condensation reaction, creating a covalent linkage. The resulting sequence, called a polypeptide, folds into a specific three-dimensional shape that enables it to perform diverse cellular functions, from catalyzing reactions to providing structural support or transporting molecules. Lipids are built from glycerol and fatty acids, not amino acid chains; nucleic acids are made from nucleotides; and carbohydrates are made from sugar units. Proteins thus fit the description as the biomolecule formed by amino acid chains linked by peptide bonds.