Which statement about polypeptide composition is true?

• A. All proteins are made from one polypeptide.
• B. Proteins are made from nucleotides.
• C. Some proteins are made from one polypeptide, some from several.
• D. Proteins are assembled from lipids.

Answer: (C)

Proteins vary in how many polypeptide chains form their functional structure. A protein can be a single polypeptide that folds into its active shape, or it can consist of several polypeptide chains that assemble together to make a functional unit. For example, myoglobin is a single-polypeptide protein, while hemoglobin is made of four polypeptide chains working together. This is why the true statement is that some proteins are made from one polypeptide and some from several. Proteins aren’t built from nucleotides (those are the building blocks of nucleic acids) and they aren’t assembled from lipids (lipids belong to a different class of biomolecules).