Chitin

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Chitin

Chitin (C

Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
₈H

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
₁₃O

Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
₅N

Nitrogen

Nitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674?. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere....
)_n is a long-chain polymer

Polymer

A polymer is a large molecule composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a variety of properties....
of a N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world. It is the main component of the cell wall

Cell wall

A cell wall is a tough, flexible and sometimes fairly rigid layer that surrounds some types of cell . It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism....
s of fungi, the exoskeleton

Exoskeleton

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 skeleton....
s of arthropod

Arthropod

Arthropods are animals belonging to the Scientific classification Arthropoda , and include the insects, arachnids, crustaceans, and others....
s, such as crustacean

Crustacean

Crustaceans are a large group of arthropods, comprising almost 52,000 described species , and are usually treated as a subphylum . They include various familiar animals, such as crabs, lobsters, crayfish, shrimp, krill and barnacles....
s (e.g.

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Encyclopedia

Chitin (C

Carbon

Hydrogen

Oxygen

Nitrogen

Polymer

Cell wall

Exoskeleton

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 skeleton....
s of arthropod

Arthropod

Arthropods are animals belonging to the Scientific classification Arthropoda , and include the insects, arachnids, crustaceans, and others....
s, such as crustacean

Crustacean

Crab

Crabs are Decapoda crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax....
s, lobster

Lobster

Clawed lobsters compose a family of large marine crustaceans. Lobsters are economically important as seafood, forming the basis of a global industry that nets United States dollar1.8 billion in trade annually....
s and shrimp

Shrimp

Shrimp are swimming, Decapoda crustaceans classified in the infraorder Caridea, found widely around the world in both fresh water and seawater. Adult shrimp are Filter feeder benthic animals living close to the bottom....
s) and insect

Insect

Insects are the biggest class of arthropods and the only ones with wings. They are the most diverse group of animals on the planet. They are most diverse at the equator and their diversity declines toward the poles....
s, including ants, beetles and butterflies, the radula

Radula

The radula is an anatomical structure found in mollusks and used for feeding. It is a minutely toothed, chitinous ribbon. It is typically used for scraping or cutting food before the food enters the esophagus....
of mollusks and the beaks of cephalopods, including squid

Squid

Squid are marine cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, Symmetry #Bilateral_symmetry, a mantle , and cephalopod arms....
and octopuses

Octopus

The octopus is a cephalopod of the order Octopoda that inhabits many diverse regions of the ocean, especially coral reefs. The term may also refer to only those creatures in the genus Octopus ....
. Chitin has also proven useful for several medical and industrial purposes. Chitin is a biological substance which may be compared to the polysaccharide cellulose

Cellulose

File:Cellulose Sessel.svgCellulose is an organic compound with the chemical formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand ? linked D-glucose units....
and to the protein keratin

Keratin

Keratins are a family of fibrous protein; tough and insoluble, they form the hard but mineral structures found in reptiles, birds, amphibians and mammals....
. Although keratin is a protein, and not a carbohydrate

Carbohydrate

Carbohydrates or saccharides are the most abundant of the four major classes of biomolecules. They fill numerous roles in living things, such as the storage and transport of energy and structural components ....
like chitin, both keratin and chitin have similar structural functions.

Chemistry, physical properties and biological function

Chitin is a polysaccharide

Polysaccharide

Polysaccharides are relatively complex carbohydrates. They are polymers made up of many monosaccharides joined together by glycosidic bonds. They are therefore very large, often branched, macromolecules....
; it is synthesized

Biosynthesis

Biosynthesis is a phenomenon wherein chemical compounds are produced from simpler reagents. Biosynthesis, unlike chemosynthesis, takes place within living organisms and is generally catalyst by enzymes....
from units of N-acetylglucosamine

N-Acetylglucosamine

N-Acetylglucosamine is a monosaccharide derivative of glucose. Chemically it is an amide between glucosamine and acetic acid. It has a molecular formula of carbon8hydrogen15nitrogenoxygen6, a molar mass of 221.21 g/mol, and it is significant in several biological systems....
(more completely, N-acetyl-D-glucos-2-amine). These units form covalent ß-1,4 linkages (similar to the linkages between glucose

Glucose

Glucose , a monosaccharide also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology....
units forming cellulose

Cellulose

Hydroxyl

Hydroxyl in chemistry stands for a molecule consisting of an oxygen atom and a hydrogen atom connected by a covalent bond. The neutral form is a hydroxyl Radical and the hydroxyl anion is called a hydroxide....
group on each monomer

Monomer

A monomer is a small molecule that may become Chemistry chemical bonding to other monomers to form a polymer....
substituted with an acetyl

Acetyl

In organic chemistry, acetyl , is a functional group, the acyl of acetic acid, with chemical formula -CarbonOxygenCarbonHydrogen3. It is sometimes abbreviated as Ac ....
amine

Amine

Amines are organic compounds and functional groups that contain a base nitrogen atom with a lone pair. Amines are derivative s of ammonia, wherein one or more hydrogen atoms are replaced by organic substituents such as alkyl and aryl groups....
group. This allows for increased hydrogen bonding between adjacent polymers, giving the chitin-polymer matrix increased strength.

In its unmodified form, chitin is translucent, pliable, resilient and quite tough. In arthropod

Arthropod

Arthropods are animals belonging to the Scientific classification Arthropoda , and include the insects, arachnids, crustaceans, and others....
s, however, it is often modified, becoming embedded in a hardened protein

Protein

Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid Residue ....
aceous matrix, which forms much of the exoskeleton

Exoskeleton

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 skeleton....
. In its pure form it is leathery, but when encrusted in calcium carbonate

Calcium carbonate

Calcium carbonate is a chemical compound with the chemical formula CalciumCarbonOxygen3. It is a common substance found as Rock in all parts of the world, and is the main component of seashells, snails, and eggshells....
it becomes much harder. The difference between the unmodified and modified forms can be seen by comparing the body wall of a caterpillar

Caterpillar

Caterpillars are the larval form of a member of the order Lepidoptera . They are mostly phytophagous in food habit, with some species being entomophagous....
(unmodified) to a beetle

Beetle

Beetles are the group of insects with the largest number of known species. They are placed in the order Coleoptera , which contains more described species than in any other order in the animal, constituting about 25% of all known life-forms....
(modified).

Chitin is one of many naturally occurring polymers. Its breakdown may be catalyzed by enzyme

Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
s called chitinase

Chitinase

Chitinases are digestive enzymes that break down glycosidic bonds in chitin. Because chitin composes the cell walls of fungi and exoskeleton elements of some animals , chitinases are generally found in organisms that either need to reshape their own chitin or to dissolve and digest the chitin of fungi or animals....
s, secreted by microorganisms such as bacteria

Bacteria

The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals....
and fungi, and produced by some plants. Some of these microorganisms have receptors to simple sugars from the decomposition of chitin. If chitin is detected, they then produce enzyme

Enzyme

Glycosidic bond

In chemistry, a glycosidic bond is a certain type of functional group that joins a carbohydrate molecule to another, which may be another carbohydrate....
s in order to convert it to simple sugars and ammonia

Ammonia

Ammonia is a chemical compound with the chemical formula nitrogenhydrogen. It is normally encountered as a gas with a characteristic pungent odor....
.

Chemically, chitin is closely related to chitosan

Chitosan

Chitosan is a linear polysaccharide composed of randomly distributed ?--linked D-glucosamine and N-Acetylglucosamine . It has a number of commercial and possible biomedical uses....
(a more water-soluble derivative of chitin). It is also closely related to cellulose

Cellulose

Glucose

Glucose , a monosaccharide also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology....
derivatives. Both materials contribute structure and strength, protecting the organism.

Fossil record

The oldest preserved chitin dates to the Oligocene

Oligocene

The Oligocene is a geologic epoch of the Paleogene Geologic Timescale and extends from about 33.9 million to 23 million years before the present....
, about .

Etymology

The English word "chitin" comes from the French

French language

French is a Romance language spoken around the world by around 80 million people as first language, by 190 million as second language, and by about another 200 million people as an acquired tongue, with significant speakers in 54 countries....
word "chitine", which first appeared in 1836. These words were derived from the Latin word "chiton", meaning mollusk. That is either influenced by, or related to the Greek

Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
word khiton
Chiton (costume)

A chiton was a form of clothing worn by men and women in Ancient Greece, from the Archaic_period_in_Greece to the Hellenistic period . There are two forms of chiton, the Dorians chiton and the later Ionians chiton....
, meaning "tunic

Tunic

A tunic is any of several types of clothing for the body, with or without sleeves, and of various lengths reaching from the shoulders to somewhere between the hips and the ankles....
" or "frock

Frock

Frock has been used since Middle Englishas the name for an article of clothing for men and women ....
", the Central Semitic

Semitic

In linguistics and ethnology, Semitic was first used to refer to a language family of largely Middle Eastern origin, now called the Semitic languages....
word "*kittan", the Akkadian

Akkadian language

Akkadian or Assyrian-Babylonian is a Semitic language that was spoken in ancient Mesopotamia. The earliest attested Semitic language, it used the cuneiform writing system derived ultimately from ancient Sumerian language, an unrelated language isolate....
words "kitû" or "kita’um", meaning flax

Flax

Flax is a member of the genus Linum in the family Linaceae. It is native to the region extending from the eastern Mediterranean region to India and was probably first domesticated in the Fertile Crescent....
or linen

Linen

Linen is a textile made from the fibers of the flax plant, Linum usitatissimum. Linen is labor-intensive to manufacture, but when it is made into garments, it is valued for its exceptional coolness and freshness in hot weather....
, and the Sumerian

Sumerian language

Sumerian was the language of ancient Sumer, spoken in Southern Mesopotamia since at least the 4th millennium BC. It was gradually replaced by Akkadian language as a spoken language somewhere around the turn of the 3rd and the 2nd millennium BC , but continued to be used as a sacred, ceremonial, literary and scientific language in Mesopotamia...
word "gada" or "gida".

A similar word, "chiton

Chiton

Chitons are small to large, primitive marine mollusks in the class Polyplacophora.There are 900 to 1,000 Extant taxon species of chitons in the class, which was formerly known as Amphineura....
", refers to a marine animal with a protective shell (also known as a "sea cradle").

Uses

Industrial

Chitin is used industrially in many processes. It is used in water purification

Water purification

This article discusses large scale, municipal water purification. For portable/emergency water purification, see Portable water purification.Water purification is the process of removing undesirable chemical and biological contaminants from raw water....
, and as an additive to thicken and stabilize foods and pharmaceuticals. It also acts as a binder in dyes, fabrics, and adhesives. Industrial separation membranes and ion-exchange resins can be made from chitin. Processes to size and strengthen paper employ chitin.

Medicine

Chitin's properties as a flexible and strong

Tensile strength

Tensile strength , or is the Stress at which a material breaks or permanently deforms. Tensile strength is an Intensive and extensive properties and, consequently, does not depend on the size of the test specimen....
material make it favorable as surgical thread. Its biodegradibility

Biodegradation

Biodegradation is the process by which organic compound substances are decomposition by the enzymes produced by living organisms. The term is often used in relation to ecology, waste management and natural environmental environmental remediation ....
means it wears away with time as the wound heals. Moreover, chitin has some unusual properties that accelerate healing of wounds in human

Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
s.

Occupations associated with high environmental chitin levels, such as shellfish processors, are prone to high incidences of asthma. Recent studies have suggested that chitin may play a role in a possible pathway in human allergic disease. Specifically, mice treated with chitin develop an allergic response, characterized by a build-up of interleukin-4 expressing innate immune cells. Treatment with a chitinase enzyme abolishes the response.

Agriculture

Most recent studies point out that chitin is a good inductor for defense mechanisms

Plant defense against herbivory

Plant defense against herbivory or host-plant resistance includes a range of adaptations evolved by plants that improve their fitness by reducing the impact of herbivores....
in plants. It was recently tested as a fertilizer

Fertilizer

Fertilizers are chemical compounds given to plants to promote growth; they are usually applied either through the soil, for uptake by plant roots, or by foliar feeding, for uptake through leaves....
that can help plants develop healthy immune responses, and have a much better yield and life expectancy.

Chitin

Chemistry, physical properties and biological function

Fossil record

Etymology

Uses

Industrial

Medicine

Agriculture

External links