Keratin Keratin Keratin () is one of a family of fibrous structural proteins. It is the key structural material making up hair, horns, claws, hooves, and the outer layer of human skin. Keratin is also the protein that protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. The only other biological matter known to approximate the toughness of keratinized tissue is chitin. Keratin derives from Greek ' from '
Vienna Convention for the Protection of the Ozone Layer Vienna Convention for the Protection of the Ozone Layer The Vienna Convention for the Protection of the Ozone Layer is a multilateral environmental agreement signed in 1985 that provided frameworks for international reductions in the production of chlorofluorocarbons due to their contribution to the destruction of the ozone layer and resulting increase in the threat of skin cancer. During the 1970's, research indicated that man-made chlorofluorocarbons (CFCs) reduce and convert ozone molecules in the atmosphere. CFCs are stable molecules composed of carbon, fluorine, and chlorine that were used prominently in products such as refrigerators. The threats associated with reduced ozone