Answer: a. to provide support and structure for cells in hair, skin, and nails
Keratin is a structural protein that is present in the epithelial cells of the epidermal layer of the skin, hair, hoofs, feathers and nails. It is also found in the internal organs and glands of animals and humans. It is a protective protein which is less prone to tearing and damage. It is insoluble in water and remains unaffected by the proteolytic enzymes (enzymes which break down proteins). Because of the physically and chemically strong structure of the keratin it supports the structure of the cells of hair, skin and nails.
