Which statement about proteins is NOT a typical function?

• A. They catalyze chemical reactions
• B. They provide structural support
• C. They transport substances
• D. They store energy

Answer: (D)

Proteins have a variety of important roles in the body, and many of them involve performing work rather than storing energy. They act as enzymes to speed up chemical reactions, providing the catalysts that metabolism relies on. They also give structure to tissues, with proteins like collagen supporting skin, bones, and connective tissue. Additionally, many proteins transport substances, such as hemoglobin carrying oxygen in the blood or channel proteins moving molecules across cell membranes. Storing energy, on the other hand, is not a primary function of proteins. Energy is mainly stored in fats and carbohydrates, while proteins are kept ready to perform work. In situations of extreme energy shortage, the body can break down proteins for energy, but that’s not their usual role.