South Dakota Cosmetology Practice Exam 2025 - Free Cosmetology Practice Questions and Study Guide

The main component of hair is keratin, which is a type of protein that forms the structure of the hair shaft. Keratin is crucial for providing strength and resilience to hair, allowing it to withstand various stresses from styling and environmental factors. The cellular structure of hair is predominantly made up of a specific type of keratin called alpha-keratin, which is also found in other body tissues such as nails and the outer layer of skin.

While collagen is an essential protein for skin elasticity and structure, it does not play a direct role in the composition of hair. Melanin is the pigment responsible for hair color, but it is not a structural component of hair. Biotin, often associated with promoting healthy hair growth, is a vitamin that supports keratin production but is not itself a component of hair. Therefore, the focus on keratin underscores its importance in forming and maintaining the integrity of hair.