Which substances help build and maintain body cells and tissues?

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

Answer: (C)

Proteins form the structural and repair components of tissues. They’re made of amino acids that assemble into long chains used to build the framework of cells and tissues, with examples like collagen in connective tissue and keratin in skin, hair, and nails. Beyond providing structure, proteins act as enzymes that drive the chemical processes necessary to maintain and renew tissues, as well as serving roles in defense, transport, and signaling. While lipids help make up cell membranes and store energy, and carbohydrates supply quick energy and some support roles, they don’t supply the primary building blocks of body tissues. Nucleic acids store and convey the genetic information that directs protein production, but the direct material for building and maintaining tissues is protein.