Animal Anatomy and Physiology 1 Practice Exam 2025 – Complete Study Resource

The primary component of hair in mammals is keratin. Keratin is a fibrous structural protein that is a key constituent not only of hair but also of nails and the outer layer of skin. It provides strength and resilience, making hair durable and able to withstand environmental stressors.

Keratin's unique properties stem from its molecular structure, which consists of long chains of amino acids that create a helical shape. This structure contributes to the rigidity and protective qualities of hair, ensuring that it can function effectively in insulating the body and offering protection to the scalp.

Other proteins mentioned, such as collagen, myosin, and elastin, serve different roles in the body. Collagen is primarily involved in providing strength and structure to connective tissues, myosin is a protein that plays a critical role in muscle contraction, and elastin is responsible for tissue elasticity. These proteins do not contribute significantly to the structural composition of hair. Thus, keratin is the essential protein that defines the composition and characteristics of hair in mammals.