What protein fiber dominates bone matrix and provides resistance to tensile forces?

• A. Collagen
• B. Elastin
• C. Fibrin
• D. Keratin

Answer: (A)

Collagen serves as the dominant protein fiber in the bone matrix, mainly type I collagen, forming a fibrous scaffold that provides tensile strength and toughness. This organic network resists pulling and bending forces and works with mineral crystals that decorate and stiffen the scaffold to give the bone its overall toughness. The combination of a collagen-rich organic matrix with mineral content makes bone a strong, yet not brittle, composite. Elastin would add elasticity in soft tissues, fibrin is involved in clotting, and keratin is a structural protein in hair and nails—none of these form the primary load-bearing framework of bone. Hence, collagen is the key component that provides resistance to tensile forces in bone.