In biology, the term cuticle or cuticula is given to a variety of tough but flexible, non-mineral outer coverings of an organism, or part of an organism, that provide protection. Foundations of modern biology There are five unifying principles They are non-homologous, differing in their origin, structure and chemical composition.

In human anatomy

Eponychium is the anatomical term for the human cuticle

In human anatomy, cuticle refers to several structures. The eponychium or cuticle in Human anatomy refers to the thickened layer of Skin surrounding fingernails and toenails. Human anatomy, which with physiology and biochemistry is a complementary basic medical science is primarily the scientific study of the morphology of the adult Human body It refers to the dead layers of epidermal cells or keratinocytes that produce the horn protein keratin, to the strip of dead skin cells at the base and sides of the fingernail, to the eponychium, and also to the superficial layer of overlapping cells covering the hair shaft (cuticula pili) that locks the hair into its follicle. Epidermis is the outermost layer of the Skin. It forms the waterproof protective wrap over the body's surface and is made up of stratified squamous Epithelium with The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called The keratinocyte is the major cell type of the epidermis, making up about 90% of epidermal cells A horn is a pointed projection of the Skin on the head of various Mammals consisting of a covering of horn ( Keratin and other Proteins Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Keratins are a family of fibrous structural proteins; tough and insoluble they form the hard but nonmineralized structures found in Reptiles Birds The skin is the outer covering of living tissue of an animal (or plant A nail is a horn -like structure at the end of an animal's Finger or Toe. The eponychium or cuticle in Human anatomy refers to the thickened layer of Skin surrounding fingernails and toenails. Hair is a keratinised protein filament that grows through the epidermis from follicles deep within the Dermis. A hair follicle is part of the Skin that grows Hair by packing old cells together

In invertebrate zoology

In zoology, the invertebrate cuticle or cuticula is a multi-layered structure outside the epidermis of many invertebrates, notably roundworms^[1] and arthropods, in which it forms an exoskeleton. Zoology (from Greek ζῷον, zoon, "animal" + λόγος, " Logos " "knowledge" is the branch of An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate Epidermis is the outermost layer of the Skin. It forms the waterproof protective wrap over the body's surface and is made up of stratified squamous Epithelium with The nematodes or roundworms ( Phylum Nematoda from Greek (nema "thread" + -ode "like" are one of the most common Arthropods are Animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, " Joint " An exoskeleton is an external Skeleton that supports and protects an animal's body in contrast to the internal Endoskeleton of for example a Human.

The main structural components of the nematode cuticle are proteins, highly cross-linked collagens and specialised insoluble proteins known as "cuticlins", together with glycoproteins and lipids. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Collagen is the main Protein of Connective tissue in Animals and the most abundant protein in Mammals making up about 50% of the whole-body protein Not to be confused with Peptidoglycan. Glycoproteins are proteins that contain Oligosaccharide chains ( Glycans) covalently attached Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble ^[2]

The main structural component of arthropod cuticle is a polysaccharide, chitin, composed of N-acetylglucosamine units, together with proteins and lipids. Polysaccharides are relatively complex Carbohydrates They are Polymers made up of many Monosaccharides joined together by Glycosidic bonds Chitin ( C 8 H 13 O 5 N)n (ˈkaɪtən is a long-chain Polymer of a N-acetylglucosamine N-Acetylglucosamine ( N-Acetyl-D-Glucosamine, or GlcNAc, or NAG) is a Monosaccharide derivative of Glucose.

In botany

Epicuticular wax covering the cuticle of a leaf of Hosta sieboldiana makes it hydrophobic. In Botany, the Plant cuticle is covered by epicuticular wax mainly consistingof straight-chain Aliphatic Hydrocarbons with a variety of substituted Plant cuticles are a protective waxy covering produced only by the epidermal cells of leaves, young shoots and all other aerial plant organs without Periderm Hosta ( syn: Funkia) is a Genus of about 23–40 Species of Lily -like plants native to northeast Asia. In Chemistry, hydrophobicity (from the combining form of water in Attic Greek hydro- and for fear phobos) refers to the physical property of Water, unable to wet the cuticle, beads up and runs off, carrying dust and soluble contamination with it. Wetting is the contact between a liquid and a solid surface resulting from intermolecular interactions when the two are brought together This property of self-cleaning ultrahydrophobicity is known as the Lotus effect

In botany, plant cuticles are protective waxy coverings produced by the epidermal cells of leaves, young shoots and all other aerial plant organs. The leaves of the sacred lotus flower ( Nelumbo) are characterized by a very high water repellency ( superhydrophobicity) Botany, plant science(s, phytology, or plant biology is a branch of Biology and is the scientific study of plant Life Plant cuticles are a protective waxy covering produced only by the epidermal cells of leaves, young shoots and all other aerial plant organs without Periderm Wax has traditionally referred to a substance that is secreted by Bees ( Beeswax) and used by them in constructing their

The main structural components of plant cuticles are the unique polymers cutin and/or cutan, impregnated with wax. Plant cuticles are a protective waxy covering produced only by the epidermal cells of leaves, young shoots and all other aerial plant organs without Periderm A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds Cutin is one of two Waxy polymers that are the main components of the Plant cuticle which covers all aerial surfaces of Plants The other major cuticle polymer Cutan is one of two Polymers which occur in the Plant cuticle. Wax has traditionally referred to a substance that is secreted by Bees ( Beeswax) and used by them in constructing their

The cuticles of plants function as permeability barriers for water and water-soluble materials. The cuticle both prevents plant surfaces from becoming wet and helps to prevent plants from drying out. Wetting is the contact between a liquid and a solid surface resulting from intermolecular interactions when the two are brought together Xerophytic plants such as cactus have very thick cuticles to help them survive in their arid climates. A xerophyte or xerophytic organism ( xero meaning dry phyte meaning plant is a Plant which is able to survive in an ecosystem with little available A cactus (plural cacti) is any member of the Spine plant family Cactaceae, native to the Americas Plants that live in range of sea's spray also tend to have thicker cuticles, to protect them from the toxic effects of salt. Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants

References

1. ^ About the roundworm cuticle
2. ^ Page, A. P. and Johnstone, I. L. (March 19, 2007) The cuticle, In: WormBook, ed. by J. M. Kramer & D. G. Moerman. The C. elegans Research Community, WormBook, doi/10. 1895/wormbook. 1. 138. 1, [1]