Final answer:
Hair is primarily made of keratin, a tough protein that forms the main structure of a hair strand. The alpha-helices of this protein build up the micro and macrofibrils of the hair.
Step-by-step explanation:
Hair is made up primarily of protein. More specifically, hair is largely composed of keratin, which is a tough protein consisting of numerous protein alpha-helices. These alpha-helices form into protofibrils, microfibrils, and eventually macrofibrils that together with dead and living cells, produce a strand of hair. The main purpose of hair includes protection from UV radiation, sensory input, and filtering debris from the air. The hair matrix is a part of the hair follicle and contains a layer of basal cells which are integral to hair growth.