Amino acids form which type of molecule?

• A. Nucleic acids
• B. Carbohydrates
• C. Polypeptides (proteins)
• D. Lipids

Answer: (C)

Amino acids link to form polypeptides, the molecules that become proteins. When amino acids join, they form peptide bonds in a dehydration reaction between the carboxyl group of one amino acid and the amino group of the next. The sequence of amino acids encodes how the chain folds into a specific three-dimensional shape, which determines the protein’s function—things like catalysis, signaling, or structural support. This is what makes proteins distinct from other macromolecules: nucleic acids are built from nucleotides, carbohydrates from sugars, and lipids from fatty acids and glycerol (or isoprenoid components). So amino acids form polypeptides, which, upon folding, function as proteins.