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1. Any of a class of filamentous proteins that are abundant in the cytoskeleton of vertebrate epithelial cells and are the main constituents of the outer layer of skin and tough epidermal structures such as hair, nails, hooves, feathers, and claws.
2. Material composed principally of keratin proteins.
ke·rat′i·nous (kə-răt′n-əs) adj.
(Zoology) a fibrous protein that occurs in the outer layer of the skin and in hair, nails, feathers, hooves, etc
ker•a•tin(ˈkɛr ə tɪn)
a tough, insoluble protein that is the main constituent of hair, nails, horn, hoofs, etc., and of the outermost layer of skin.
ke•rat•i•nous (kəˈræt n əs) adj.
A tough, fibrous protein that is the main structural component of hair, nails, horns, feathers, and hooves.
Did You Know? Nature ingeniously uses the same chemicals to perform a wide variety of functions in living things. An example is the group of closely related proteins known as the keratins. When nature wants something hard and tough for an animal, it turns to keratins. Your nails and hair are made mostly of a kind of keratin, and so are a dog's claws, a bird's beak, and a goat's horns. Even the hard material called baleen that some whales have in their mouths to help them eat is made of a variety of keratin. All proteins are strings of amino acids, and the keratins' secret is the amino acid known as cysteine. This amino acid tends to form strong bonds with other cysteines in the protein. The different keratins vary in hardness, depending on how many cysteine bonds are present. The bonds are what make the keratins tough as, well, nails.
A hard, waterproof protein found in the epidermis, hair, and nails.
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|Noun||1.||keratin - a fibrous scleroprotein that occurs in the outer layer of the skin and in horny tissues such as hair, feathers, nails, and hooves|
feather, plumage, plume - the light horny waterproof structure forming the external covering of birds
hair - a covering for the body (or parts of it) consisting of a dense growth of threadlike structures (as on the human head); helps to prevent heat loss; "he combed his hair"; "each hair consists of layers of dead keratinized cells"
horn - the material (mostly keratin) that covers the horns of ungulates and forms hooves and claws and nails