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Polysaccharides (), or polycarbohydrates, are the most abundant
carbohydrate A carbohydrate () is a biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a ...
found in
food Food is any substance consumed to provide Nutrient, nutritional support for an organism. Food is usually of plant, animal or Fungus, fungal origin, and contains essential nutrients, such as carbohydrates, fats, protein (nutrient), proteins, vi ...

food
. They are long chain
polymeric A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance, a material with a definite chemical ...
carbohydrates composed of
monosaccharide Monosaccharides (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is ap ...
units bound together by glycosidic linkages. This carbohydrate can react with water (
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution Substitution may refer to: Arts and media *Chord substitution, in music, swapping one chord for ...

hydrolysis
) using amylase enzymes as catalyst, which produces constituent sugars (
monosaccharides Monosaccharides (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 ...
, or
oligosaccharide An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide is a disaccharide A disaccharide (also called a double sugar or ''biose'') is the sug ...
s). They range in structure from linear to highly branched. Examples include storage polysaccharides such as
starch Starch or amylum is a consisting of numerous units joined by s. This is produced by most green s for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in s like , es, (corn), , ...
,
glycogen Glycogen is a multibranched polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant found in . They are long chain carbohydrates composed of units bound together by . This carbohydrate can react with water () usi ...

glycogen
and
galactogen
galactogen
and structural polysaccharides such as
cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important stru ...

cellulose
and
chitin units that repeat to form long chains in β-(1→4)-linkage. of the chitin molecule. Chitin ( carbon, C8H13O5N)n ( ) is a long-chain polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical su ...

chitin
. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure, these
macromolecule macromolecule A macromolecule is a very large molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically neu ...
s can have distinct properties from their monosaccharide building blocks. They may be
amorphous In condensed matter physics Condensed matter physics is the field of physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science th ...

amorphous
or even
insoluble In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds composed of atom ...
in water. When all the monosaccharides in a polysaccharide are the same type, the polysaccharide is called a ''homopolysaccharide'' or ''homoglycan'', but when more than one type of monosaccharide is present they are called ''heteropolysaccharides'' or ''heteroglycans''. Natural saccharides are generally composed of simple carbohydrates called
monosaccharide Monosaccharides (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is ap ...
s with general formula (CH2O)''n'' where ''n'' is three or more. Examples of monosaccharides are
glucose Glucose is a simple with the . Glucose is the most abundant , a subcategory of s. Glucose is mainly made by and most during from water and carbon dioxide, using energy from sunlight, where it is used to make in s, the most abundant carbohydr ...

glucose
,
fructose Fructose, or fruit sugar, is a ketonic simple sugar Monosaccharides (from Greek language, Greek ''wikt:μόνος, monos'': single, ''sacchar'': sugar), also called simple sugars, are the simplest form of sugar and the most basic units (monomers ...

fructose
, and
glyceraldehyde Glyceraldehyde (glyceral) is a triose is an aldotriose because the carbonyl group is at the end of the chain Image:Dihydroxyacetone.png">150px, Dihydroxyacetone is a ketone, ketotriose because the carbonyl group is the center of the chain. A tr ...

glyceraldehyde
. Polysaccharides, meanwhile, have a general formula of C''x''(H2O)''y'' where ''x'' is usually a large number between 200 and 2500. When the repeating units in the polymer backbone are six-carbon monosaccharides, as is often the case, the general formula simplifies to (C6H10O5)''n'', where typically . As a rule of thumb, polysaccharides contain more than ten monosaccharide units, whereas
oligosaccharide An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide is a disaccharide A disaccharide (also called a double sugar or ''biose'') is the sug ...
s contain three to ten monosaccharide units; but the precise cutoff varies somewhat according to convention. Polysaccharides are an important class of biological polymers. Their
function Function or functionality may refer to: Computing * Function key A function key is a key on a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern comp ...
in living organisms is usually either structure- or storage-related.
Starch Starch or amylum is a consisting of numerous units joined by s. This is produced by most green s for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in s like , es, (corn), , ...
(a polymer of glucose) is used as a storage polysaccharide in plants, being found in the form of both
amylose Amylose is a polysaccharide , a beta-glucan polysaccharide Image:amylose 3Dprojection.svg">350px, Amylose is a linear polymer of glucose mainly linked with α(1→4) bonds. It can be made of several thousands of glucose units. It is one of the two ...

amylose
and the branched
amylopectin Amylopectin is a water-soluble Subscription required for online access. polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose. Glucose units are linke ...
. In animals, the structurally similar glucose polymer is the more densely branched
glycogen Glycogen is a multibranched polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant found in . They are long chain carbohydrates composed of units bound together by . This carbohydrate can react with water () usi ...

glycogen
, sometimes called "animal starch". Glycogen's properties allow it to be metabolized more quickly, which suits the active lives of moving animals. In
bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typ ...

bacteria
, they play an important role in bacterial multicellularity.
Cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important stru ...

Cellulose
and
chitin units that repeat to form long chains in β-(1→4)-linkage. of the chitin molecule. Chitin ( carbon, C8H13O5N)n ( ) is a long-chain polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical su ...

chitin
are examples of structural polysaccharides. Cellulose is used in the
cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane cell membrane vs. Prokaryotes The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to a ...
s of plants and other organisms and is said to be the most abundant
organic molecule , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carbon's ability to Catenation, catenate (form chains with other carbon ...
on Earth. It has many uses such as a significant role in the paper and textile industries, and is used as a feedstock for the production of rayon (via the
viscose Rayon is a synthetic fiber Synthetic fiber or synthetic fibre (in British English; American and British English spelling differences#-re, -er, see spelling differences) are fibers made by humans through chemical synthesis, as opposed to natur ...
process), cellulose acetate, celluloid, and nitrocellulose. Chitin has a similar structure, but has
nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

nitrogen
-containing side branches, increasing its strength. It is found in
arthropod An arthropod (, (gen. ποδός)) is an invertebrate Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This includes all animals apart fr ...
exoskeleton An exoskeleton (from Greek έξω, ''éxō'' "outer" and σκελετός, ''skeletós'' "skeleton") is the external skeleton A skeleton is a structural frame that supports an animal Animals (also called Metazoa) are multicellular ...

exoskeleton
s and in the cell walls of some
fungi A fungus (plural The plural (sometimes abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters, or words taken from the full ...

fungi
. It also has multiple uses, including
surgical thread Surgical suture is a medical device Artificial pacemaker, a Class III device in the United States A medical device is any device intended to be used for medical purposes. Medical devices benefit patients by helping health care providers diagnos ...
s. Polysaccharides also include
callose Callose is a plant polysaccharide , a beta-glucan is an example of a (1→4)-β-D-glucan composed of glucose Glucose is a simple sugar with the Chemical formula#Molecular formula, molecular formula . Glucose is the most abundant monosaccharide ...

callose
or
laminarin The molecule laminarin (also known as laminaran) is a storage glucan (a polysaccharide , a beta-glucan polysaccharide Image:amylose 3Dprojection.svg">350px, Amylose is a linear polymer of glucose mainly linked with α(1→4) bonds. It can be mad ...
,
chrysolaminarin Chrysolaminarin is a linear polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of penta ...
,
xylan Xylan (; ) (CAS number A CAS Registry Number, also referred to as CASRN or CAS Number, is a unique numerical identifier An identifier is a name that identifies (that is, labels the identity of) either a unique object or a unique ''class'' of ...

xylan
,
arabinoxylanArabinoxylan is a hemicellulose found in both the primary and secondary cell walls of plants, including woods and cereal grains, consisting of copolymers of two pentose sugars: arabinose and xylose. Structure Arabinoxylan chains contain a large numb ...
, mannan,
fucoidan Fucoidan is a long chain sulfate The sulfate or sulphate ion is a polyatomic anion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has m ...

fucoidan
and
galactomannan A segment of galactomannan showing mannose backbone (below) with a branching galactose unit (top) Galactomannans are polysaccharide , a beta-glucan polysaccharide Image:amylose 3Dprojection.svg">350px, Amylose is a linear polymer of glucose mainl ...

galactomannan
.


Function


Structure

Nutrition polysaccharides are common sources of energy. Many organisms can easily break down starches into glucose; however, most organisms cannot metabolize cellulose or other polysaccharides like
cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important stru ...

cellulose
,
chitin units that repeat to form long chains in β-(1→4)-linkage. of the chitin molecule. Chitin ( carbon, C8H13O5N)n ( ) is a long-chain polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical su ...

chitin
and arabinoxylans. These carbohydrate types can be metabolized by some bacteria and protists.
Ruminant Ruminants (suborder Ruminantia) are large ungulate, hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by Enteric fermentation, fermenting it in a specialized stomach prior to digestion, princi ...
s and
termite Termites are Eusociality, eusocial insects that are classified at the Taxonomy (biology), taxonomic rank of infraorder Isoptera, or alternatively as Taxonomic rank#All ranks, epifamily Termitoidae, within the order Blattodea (along with cockroa ...

termite
s, for example, use microorganisms to process
cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important stru ...

cellulose
. Even though these complex polysaccharides are not very digestible, they provide important dietary elements for humans. Called
dietary fiber Dietary fiber (British spelling fibre) or roughage is the portion of plant-derived food that cannot be completely broken down by human digestive enzyme Digestive may refer to: Biology *Digestion Digestion is the breakdown of large insolub ...
, these carbohydrates enhance digestion among other benefits. The main action of dietary fiber is to change the nature of the contents of the
gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system The human digestive system consists of the gastrointestinal tract The gastrointestinal tract, (GI tract, GIT, d ...
, and to change how other nutrients and chemicals are absorbed. Soluble fiber binds to
bile acids Bile acids are steroid , hypothetical a steroid with 32 carbon atoms. Its core ring system (ABCD), composed of 17 carbon atoms, is shown with IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federatio ...
in the small intestine, making them less likely to enter the body; this in turn lowers
cholesterol Cholesterol is any of a class of certain organic compound, organic molecules. A cholesterol is a sterol (or chemical modification, modified steroid), a type of lipid. Cholesterol is biosynthesis, biosynthesized by all animal Cell (biology)#Euk ...

cholesterol
levels in the blood. Soluble fiber also attenuates the absorption of sugar, reduces sugar response after eating, normalizes blood lipid levels and, once fermented in the colon, produces
short-chain fatty acidShort-chain fatty acids (SCFAs) are fatty acids with fewer than six carbon atoms. Derived from intestine, intestinal microbe, microbial fermentation of indigestible foods, SCFAs are the main energy source of Gastrointestinal_tract#Mucosa, colonocytes ...
s as byproducts with wide-ranging physiological activities (discussion below). Although insoluble fiber is associated with reduced diabetes risk, the mechanism by which this occurs is unknown. Not yet formally proposed as an essential macronutrient (as of 2005), dietary fiber is nevertheless regarded as important for the diet, with regulatory authorities in many developed countries recommending increases in fiber intake.


Storage polysaccharides


Starch

Starch Starch or amylum is a consisting of numerous units joined by s. This is produced by most green s for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in s like , es, (corn), , ...
is a
glucose Glucose is a simple with the . Glucose is the most abundant , a subcategory of s. Glucose is mainly made by and most during from water and carbon dioxide, using energy from sunlight, where it is used to make in s, the most abundant carbohydr ...

glucose
polymer in which
glucopyranose Glucose is a simple sugar Sugar is the generic name for Sweetness, sweet-tasting, soluble carbohydrates, many of which are used in food. Table sugar, granulated sugar, or regular sugar, refers to sucrose, a disaccharide composed of glucose and ...

glucopyranose
units are bonded by ''alpha''-linkages. It is made up of a mixture of
amylose Amylose is a polysaccharide , a beta-glucan polysaccharide Image:amylose 3Dprojection.svg">350px, Amylose is a linear polymer of glucose mainly linked with α(1→4) bonds. It can be made of several thousands of glucose units. It is one of the two ...

amylose
(15–20%) and
amylopectin Amylopectin is a water-soluble Subscription required for online access. polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose. Glucose units are linke ...
(80–85%). Amylose consists of a linear chain of several hundred glucose molecules, and Amylopectin is a branched molecule made of several thousand glucose units (every chain of 24–30 glucose units is one unit of Amylopectin). Starches are
insoluble In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds composed of atom ...
in
water Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known li ...

water
. They can be digested by breaking the ''alpha''-linkages (glycosidic bonds). Both humans and other animals have amylases, so they can digest starches.
Potato The potato is a starch#Food, starchy tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial plant, perennial in the nightshade family Solanaceae. Wild potato species can be found thro ...

Potato
,
rice Rice is the seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was relea ...

rice
,
wheat Wheat is a grass widely cultivated for its seed, a cereal grain which is a worldwide staple food. The many species of wheat together make up the genus ''Triticum''; the most widely grown is common wheat Common wheat (''Triticum aestivum'' ...

wheat
, and
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It can also be ...

maize
are major sources of starch in the human diet. The formations of starches are the ways that plants store
glucose Glucose is a simple with the . Glucose is the most abundant , a subcategory of s. Glucose is mainly made by and most during from water and carbon dioxide, using energy from sunlight, where it is used to make in s, the most abundant carbohydr ...

glucose
.


Glycogen

Glycogen serves as the secondary long-term energy storage in
animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells ...

animal
and
fungal A fungus (plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of a noun typically denotes a quantity great ...

fungal
cells, with the primary energy stores being held in
adipose tissue Adipose tissue, body fat, or simply fat is a loose connective tissue Connective tissue is one of the many basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biolo ...

adipose tissue
. Glycogen is made primarily by the
liver The liver is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's t ...

liver
and the
muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly cat ...

muscle
s, but can also be made by
glycogenesis Glycogenesis is the process of glycogen A view of the atomic structure of a single branched strand of glucose units in a glycogen molecule. Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in an ...

glycogenesis
within the
brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tis ...

brain
and
stomach The stomach is a muscular, in the of humans and many other animals, including several s. The stomach has a dilated structure and functions as a vital organ. In the digestive system the stomach is involved in the second phase of digestion, ...

stomach
. Glycogen is analogous to
starch Starch or amylum is a consisting of numerous units joined by s. This is produced by most green s for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in s like , es, (corn), , ...
, a glucose polymer in
plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, can later be released to fuel ...

plant
s, and is sometimes referred to as ''animal starch'', having a similar structure to
amylopectin Amylopectin is a water-soluble Subscription required for online access. polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose. Glucose units are linke ...
but more extensively branched and compact than starch. Glycogen is a polymer of α(1→4) glycosidic bonds linked, with α(1→6)-linked branches. Glycogen is found in the form of granules in the
cytosol The cytosol, also known as cytoplasmic matrix or groundplasm, is one of the liquids found inside cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Closed spaces * Monastic cell, a s ...
/cytoplasm in many cell types, and plays an important role in the
glucose cycle The glucose cycle (also known as the hepatic futile cycle) occurs primarily in the liver The liver is an organ only found in vertebrates which detoxifies various metabolites, synthesizes proteins and produces biochemicals necessary for diges ...
. Glycogen forms an
energy In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regula ...

energy
reserve that can be quickly mobilized to meet a sudden need for glucose, but one that is less compact and more immediately available as an energy reserve than
triglycerides 300px, Example of an unsaturated fat triglyceride (C55H98O6). Left part: glycerol; right part, from top to bottom: palmitic acid, oleic acid">palmitic_acid.html" ;"title="glycerol; right part, from top to bottom: palmitic acid">glycerol; right par ...
(lipids). In the liver
hepatocyte A hepatocyte is a cell of the main parenchymal tissue of the liver. Hepatocytes make up 80% of the liver's mass. These cells are involved in: * Protein biosynthesis, Protein synthesis * Storage protein, Protein storage * Transformation of carbohyd ...
s, glycogen can compose up to 8 percent (100–120 grams in an adult) of the fresh weight soon after a meal. Only the glycogen stored in the liver can be made accessible to other organs. In the
muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly cat ...

muscle
s, glycogen is found in a low
concentration In chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in t ...

concentration
of one to two percent of the muscle mass. The amount of glycogen stored in the body—especially within the
muscles Skeletal muscles (commonly referred to as muscles) are Organ (biology), organs of the vertebrate muscular system that are mostly attached by tendons to bones of the skeleton. The muscle cells of skeletal muscles are much longer than in the other ...

muscles
,
liver The liver is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's t ...

liver
, and
red blood cells Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

red blood cells
—varies with physical activity, basal metabolic rate, and eating habits such as
intermittent fasting Intermittent fasting, also known as intermittent energy restriction, is any of various meal timing schedules that cycle between voluntary fasting (or reduced calorie intake) and non-fasting over a given period. Methods of intermittent fasting inc ...

intermittent fasting
. Small amounts of glycogen are found in the
kidney The kidneys are two reddish-brown bean-shaped organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized ...

kidney
s, and even smaller amounts in certain
glial Glia, also called glial cells (singular ''gliocyte'') or neuroglia, are non-neuron A neuron or nerve cell is an membrane potential#Cell excitability, electrically excitable cell (biology), cell that communicates with other cells via specializ ...
cells in the
brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tis ...

brain
and
white blood cells White blood cells, also called leukocytes or leucocytes, are the cell (biology), cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and de ...
. The uterus also stores glycogen during pregnancy, to nourish the embryo. Glycogen is composed of a branched chain of glucose residues. It is stored in liver and muscles. *It is an energy reserve for animals. *It is the chief form of carbohydrate stored in animal body. *It is insoluble in water. It turns brown-red when mixed with iodine. *It also yields glucose on
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution Substitution may refer to: Arts and media *Chord substitution, in music, swapping one chord for ...

hydrolysis
. File:Glycogen structure.svg, Schematic 2-D cross-sectional view of glycogen. A core protein of glycogenin is surrounded by branches of
glucose Glucose is a simple with the . Glucose is the most abundant , a subcategory of s. Glucose is mainly made by and most during from water and carbon dioxide, using energy from sunlight, where it is used to make in s, the most abundant carbohydr ...

glucose
units. The entire globular granule may contain approximately 30,000 glucose units. File:Glycogen spacefilling model.jpg, A view of the
atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of ato ...

atom
ic structure of a single branched strand of
glucose Glucose is a simple with the . Glucose is the most abundant , a subcategory of s. Glucose is mainly made by and most during from water and carbon dioxide, using energy from sunlight, where it is used to make in s, the most abundant carbohydr ...

glucose
units in a glycogen
molecule A molecule is an electrically Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position In physics, motion is the phenomenon ...

molecule
.


Galactogen

Galactogen is a polysaccharide of
galactose Galactose (, '' galacto-'' + ''-ose The suffix In linguistics Linguistics is the science, scientific study of language. It encompasses the analysis of every aspect of language, as well as the methods for studying and modeling them. Th ...
that functions as energy storage in
pulmonate Pulmonata, or "pulmonates", is an informal group (previously an order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean ...

pulmonate
snails and some
Caenogastropoda Caenogastropoda is a taxonomic clade A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural group, is a group of organisms that are monophyly, monophyletic—that is, composed of a common ancestor and al ...

Caenogastropoda
. This polysaccharide is exclusive of the reproduction and is only found in the albumen gland from the female snail reproductive system and in the perivitelline fluid of eggs. Galactogen serves as an energy reserve for developing embryos and hatchlings, which is later replaced by
glycogen Glycogen is a multibranched polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant found in . They are long chain carbohydrates composed of units bound together by . This carbohydrate can react with water () usi ...

glycogen
in juveniles and adults.


Inulin

Inulin Inulins are a group of naturally occurring polysaccharides produced by many types of plants, industrially most often extracted from chicory. The inulins belong to a class of dietary fibers known as fructans. Inulin is used by some plants as a mean ...

Inulin
is a naturally occurring polysaccharide
complex carbohydrate is a disaccharide found in animal milk. It consists of a molecule of galactose, D-galactose and a molecule of glucose, D-glucose bonded by beta-1-4 glycosidic linkage. A carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) an ...
composed of
fructose Fructose, or fruit sugar, is a ketonic simple sugar Monosaccharides (from Greek language, Greek ''wikt:μόνος, monos'': single, ''sacchar'': sugar), also called simple sugars, are the simplest form of sugar and the most basic units (monomers ...

fructose
, a plant-derived food that cannot be completely broken down by human digestive enzymes.


Structural polysaccharides


Arabinoxylans

ArabinoxylanArabinoxylan is a hemicellulose found in both the primary and secondary cell walls of plants, including woods and cereal grains, consisting of copolymers of two pentose sugars: arabinose and xylose. Structure Arabinoxylan chains contain a large numb ...
s are found in both the primary and secondary cell walls of plants and are the copolymers of two sugars:
arabinose Arabinose is an aldopentose – a monosaccharide Monosaccharides (from Greek '' monos'': single, ''sacchar'': sugar), also called simple sugars, are the simplest form of sugar Sugar is the generic name for Sweetness, sweet-tasting, soluble ...

arabinose
and
xylose Xylose ( grc, ξύλον, , "wood") is a sugar first isolated from wood, and named for it. Xylose is classified as a of the type, which means that it contains five atoms and includes an . It is derived from , one of the main constituents o ...

xylose
. They may also have beneficial effects on human health.


Cellulose

The structural components of
plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, can later be released to fuel ...

plant
s are formed primarily from
cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important stru ...

cellulose
. Wood is largely cellulose and
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and Bark (botany), bark, because they l ...

lignin
, while
paper Paper is a thin sheet material Material is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance, a material with a definite chemical composition ...

paper
and
cotton Cotton is a soft, fluffy staple fiber Fiber or fibre (from la, fibra, links=no) is a natural Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of s ...

cotton
are nearly pure cellulose. Cellulose is a
polymer A polymer (; Greek ''poly- Poly, from the Greek :wikt:πολύς, πολύς meaning "many" or "much", may refer to: Businesses * China Poly Group Corporation, a Chinese business group, and its subsidiaries: ** Poly Property, a Hong Kong inc ...

polymer
made with repeated glucose units bonded together by ''beta''-linkages. Humans and many animals lack an enzyme to break the ''beta''-linkages, so they do not digest cellulose. Certain animals such as
termite Termites are Eusociality, eusocial insects that are classified at the Taxonomy (biology), taxonomic rank of infraorder Isoptera, or alternatively as Taxonomic rank#All ranks, epifamily Termitoidae, within the order Blattodea (along with cockroa ...

termite
s can digest cellulose, because bacteria possessing the enzyme are present in their gut. Cellulose is insoluble in water. It does not change color when mixed with iodine. On hydrolysis, it yields glucose. It is the most abundant carbohydrate in nature.


Chitin

Chitin Chitin (carbon, C8hydrogen, H13oxygen, O5nitrogen, N)n ( ) is a long-chain polymer of N-Acetylglucosamine, ''N''-acetylglucosamine, an amide derivative of glucose. The second most abundant polysaccharide in nature (behind only cellulose), it ...

Chitin
is one of many naturally occurring
polymers A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, substance or material consisting of very large molecules, or macromolecules, composed of many Repeat unit, repeating subunits. Due to thei ...

polymers
. It forms a structural component of many animals, such as
exoskeleton An exoskeleton (from Greek έξω, ''éxō'' "outer" and σκελετός, ''skeletós'' "skeleton") is the external skeleton A skeleton is a structural frame that supports an animal Animals (also called Metazoa) are multicellular ...

exoskeleton
s. Over time it is bio-degradable in the natural environment. Its breakdown may be catalyzed by
enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates in ...

enzyme
s called
chitinase Chitinases (''chitodextrinase'', ''1,4-beta-poly-N-acetylglucosaminidase'', ''poly-beta-glucosaminidase'', ''beta-1,4-poly-N-acetyl glucosamidinase'', ''poly ,4-(N-acetyl-beta-D-glucosaminide)glycanohydrolase'', ''(1->4)-2-acetamido-2-deoxy-beta ...
s, secreted by microorganisms such as
bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typ ...

bacteria
and
fungi A fungus (plural The plural (sometimes abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters, or words taken from the full ...

fungi
and produced by some plants. Some of these microorganisms have
receptors Receptor may refer to: *Sensory receptor, in physiology, any structure which, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds to a ne ...
to simple
sugars Sugar is the generic name for Sweetness, sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides o ...
from the decomposition of chitin. If chitin is detected, they then produce
enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates in ...

enzyme
s to digest it by cleaving the
glycosidic bond A glycosidic bond or glycosidic linkage is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate. A glycosidic bond is formed between the hemiacetal or hemiketal group ...
s in order to convert it to simple sugars and
ammonia Ammonia is a chemical compound, compound of nitrogen and hydrogen with the chemical formula, formula NH3. A Binary compounds of hydrogen, stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct ch ...

ammonia
. Chemically, chitin is closely related to
chitosan Chitosan is a linear polysaccharide composed of randomly distributed β-(1→4)-linked Glucosamine, D-glucosamine (deacetylated unit) and N-Acetylglucosamine, ''N''-acetyl-D-glucosamine (acetylated unit). It is made by treating the chitin shells ...

chitosan
(a more water-soluble derivative of chitin). It is also closely related to
cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important stru ...

cellulose
in that it is a long unbranched chain of
glucose Glucose is a simple with the . Glucose is the most abundant , a subcategory of s. Glucose is mainly made by and most during from water and carbon dioxide, using energy from sunlight, where it is used to make in s, the most abundant carbohydr ...

glucose
derivatives. Both materials contribute structure and strength, protecting the organism.


Pectins

Pectin Pectin (from grc, πηκτικός ', "congealed, curdled") is a structural acidic heteropolysaccharide contained in the primary and middle lamella The middle lamella is a layer that cements together the primary cell wall A cell wall is a ...

Pectin
s are a family of complex polysaccharides that contain 1,4-linked α--galactosyl uronic acid residues. They are present in most primary cell walls and in the nonwoody parts of terrestrial plants.


Acidic polysaccharides

Acidic polysaccharides are polysaccharides that contain
carboxyl group A carboxylic acid is an organic acid that contains a carboxyl group (C(=O)OH) attached to an R-group. The general formula of a carboxylic acid is R−COOH or R−CO2H, with substituent, R referring to the alkyl, alkenyl, aryl, or other group. ...

carboxyl group
s, phosphate groups and/or groups.


Bacterial polysaccharides

Pathogenic bacteria Pathogenic bacteria are bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of biological cell The cell (from Latin ''cella'', meaning "small room") is the basic structural, functional, and biological unit of a ...
commonly produce a thick, mucous-like, layer of polysaccharide. This "capsule" cloaks
antigen In immunology Immunology is a branch of biology that covers the study of immune systems in all organisms. Immunology charts, measures, and contextualizes the Physiology, physiological functioning of the immune system in states of both health ...
ic
protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a No ...

protein
s on the bacterial surface that would otherwise provoke an immune response and thereby lead to the destruction of the bacteria. Capsular polysaccharides are water-soluble, commonly acidic, and have
molecular weight A molecule is an electrically Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position In physics, motion is the phenomenon ...
s on the order of 100,000 to 2,000,000 daltons. They are linear and consist of regularly repeating subunits of one to six
monosaccharide Monosaccharides (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is ap ...
s. There is enormous structural diversity; nearly two hundred different polysaccharides are produced by '''' alone. Mixtures of capsular polysaccharides, either conjugated or native, are used as
vaccine A vaccine is a biological preparation that provides active acquired immunity The adaptive immune system, also referred as the acquired immune system, is a subsystem of the immune system The immune system is a network of biological process ...

vaccine
s. Bacteria and many other microbes, including
fungi A fungus (plural The plural (sometimes abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters, or words taken from the full ...

fungi
and
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic Photosynthesis is a process used by plants and other organisms to convert Conversion or convert may refer to: Arts, entertainment, and media * Co ...

algae
, often secrete polysaccharides to help them adhere to surfaces and to prevent them from drying out. Humans have developed some of these polysaccharides into useful products, including
xanthan gum Xanthan gum () is a polysaccharide with many industrial uses, including as a common food additive. It is an effective thickening agent and stabilizer (food), stabilizer to prevent ingredients from separating. It can be produced from monosacchar ...
,
dextran Dextran is a complex branched glucan (polysaccharide , a beta-glucan polysaccharide Image:amylose 3Dprojection.svg">350px, Amylose is a linear polymer of glucose mainly linked with α(1→4) bonds. It can be made of several thousands of glucose ...

dextran
, welan gum, gellan gum, diutan gum and pullulan. Levan-type exopolysaccharide produced by ''Pantoea agglomerans'' ZMR7 was reported to decrease the viability of rhabdomyosarcoma (RD) and breast cancer (MDA) cells compared with untreated cancer cells. In addition, it has high antiparasitic activity against the promastigote of ''Leishmania tropica.'' Most of these polysaccharides exhibit useful visco-elastic properties when dissolved in water at very low levels. This makes various liquids used in everyday life, such as some foods, lotions, cleaners, and paints, viscous when stationary, but much more free-flowing when even slight shear is applied by stirring or shaking, pouring, wiping, or brushing. This property is named pseudoplasticity or shear thinning; the study of such matters is called rheology. : Aqueous solutions of the polysaccharide alone have a curious behavior when stirred: after stirring ceases, the solution initially continues to swirl due to momentum, then slows to a standstill due to viscosity and reverses direction briefly before stopping. This recoil is due to the elastic effect of the polysaccharide chains, previously stretched in solution, returning to their relaxed state. Cell-surface polysaccharides play diverse roles in bacterial ecology and physiology. They serve as a barrier between the
cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane cell membrane vs. Prokaryotes The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to a ...
and the environment, mediate host-pathogen interactions. Polysaccharides also play an important role in formation of Biofilm, biofilms and the structuring of complex life forms in bacteria like ''Myxococcus xanthus'.'' These polysaccharides are synthesized from nucleotide-activated precursors (called nucleotide sugars) and, in most cases, all the enzymes necessary for biosynthesis, assembly and transport of the completed polymer are encoded by genes organized in dedicated clusters within the genome of the organism. Lipopolysaccharide is one of the most important cell-surface polysaccharides, as it plays a key structural role in outer membrane integrity, as well as being an important mediator of host-pathogen interactions. The enzymes that make the ''A-band'' (homopolymeric) and ''B-band'' (heteropolymeric) O-antigens have been identified and the metabolic pathways defined. The exopolysaccharide alginate is a linear copolymer of β-1,4-linked -mannuronic acid and -guluronic acid residues, and is responsible for the mucoid phenotype of late-stage cystic fibrosis disease. The ''pel'' and ''psl'' loci are two recently discovered gene clusters that also encode exopolysaccharides found to be important for biofilm formation. Rhamnolipid is a biosurfactant whose production is tightly regulated at the Transcription (genetics), transcriptional level, but the precise role that it plays in disease is not well understood at present. Protein glycosylation, particularly of pilin and flagellin, became a focus of research by several groups from about 2007, and has been shown to be important for adhesion and invasion during bacterial infection.


Chemical identification tests for polysaccharides


Periodic acid-Schiff stain (PAS)

Polysaccharides with unprotected Diol#Vicinal diols, vicinal diols or amino sugars (where some hydroxyl groups are replaced with amines) give a positive periodic acid-Schiff stain (PAS). The list of polysaccharides that stain with PAS is long. Although mucins of epithelial origins stain with PAS, mucins of connective tissue origin have so many acidic substitutions that they do not have enough glycol or amino-alcohol groups left to react with PAS.


See also

*Glycan *Oligosaccharide nomenclature *Polysaccharide encapsulated bacteria


References


External links


Polysaccharide Structure

European Polysaccharide Network of Excellence
{{Authority control Polysaccharides, Carbohydrate chemistry