Which of the following is an example of a macromolecule?

Which of the following is an example of a macromolecule?

• A. Water
• B. DNA
• C. Sodium chloride
• D. Ammonia

Answer: (B)

Macromolecules are large biological polymers made from many repeating subunits. DNA fits this description because it is a nucleic acid built from long chains of nucleotides linked together by phosphodiester bonds. Each nucleotide contains a sugar, a phosphate, and a base, so the chain is a polymer with a very high molecular weight. That size and polymeric nature make DNA a macromolecule. In contrast, water is a small molecule, sodium chloride is an ionic compound, and ammonia is a simple molecule—none of these form long polymer chains or have the high molecular weight characteristic of macromolecules.

Macromolecules are large biological polymers made from many repeating subunits. DNA fits this description because it is a nucleic acid built from long chains of nucleotides linked together by phosphodiester bonds. Each nucleotide contains a sugar, a phosphate, and a base, so the chain is a polymer with a very high molecular weight. That size and polymeric nature make DNA a macromolecule. In contrast, water is a small molecule, sodium chloride is an ionic compound, and ammonia is a simple molecule—none of these form long polymer chains or have the high molecular weight characteristic of macromolecules.