Cellulose

Cellulose is made up of long strings of glucose strung together in Beta linkages. Cellulose in a molecule which is created by plants and can only be broken down be animals with the necessary amino acids. Humans are unable to break down cellulose. It is also known as fiber, so although we cant break it down it is an integral part of our dietary needs. Cotton is another example of how we interface with cellulose every day. Cotton is made up of cellulose and so all of our cotton clothing is actually made up of glucose at a molecular level. Cellulose's molecular formula is C6H10O5 Fruit tissues are made of cellulose and that is why it sometimes appears stringy and very hard to chew Cellulose is not a water soluble molecule Cellulose can be broken down chemically into its glucose units by treating it with concentrated acids at high temperature.

The major component in the rigid cell walls in plants is cellulose. Cellulose is a linear polysaccharides polymer with many glucose monosaccharide units. The acetal linkage is beta which makes it different from starch. This peculiar difference in acetal linkages results in a major difference in digestibility in humans. Humans are unable to digest cellulose because the appropriate enzymes to breakdown the beta acetal linkages are lacking.



Places we see Cellulose: 1. cardboard 2. cotton 3. Linnen 4. cellophane 5. rayon6. smokeless gunpowder 7. adhesives 8. binders

Structure and properties
Cellulose has no taste, is odorless, is [|hydrophilic] with the [|contact angle] of 20–30, [|[13]] is insoluble in [|water] and most organic [|solvents], is [|chiral] and is [|biodegradable]. It can be broken down chemically into its glucose units by treating it with concentrated acids at high temperature. Cellulose is derived from D -glucose units, which [|condense] through β(1→4)- [|glycosidic bonds]. This linkage motif contrasts with that for α(1→4)-glycosidic bonds present in [|starch], [|glycogen] , and other carbohydrates. Cellulose is a straight chain polymer: unlike starch, no coiling or branching occurs, and the molecule adopts an extended and rather stiff rod-like conformation, aided by the equatorial conformation of the glucose residues. The multiple [|hydroxyl groups] on the glucose from one chain form [|hydrogen bonds] with oxygen atoms on the same or on a neighbor chain, holding the chains firmly together side-by-side and forming //microfibrils// with high [|tensile strength]. This strength is important in cell walls, where the microfibrils are meshed into a carbohydrate //matrix//, conferring rigidity to plant cells.    A triple strand of cellulose showing the hydrogen bonds (cyan lines) between glucose strands Compared to starch, cellulose is also much more [|crystalline]. Whereas starch undergoes a crystalline to [|amorphous] transition when heated beyond 60–70 °C in water (as in cooking), cellulose requires a temperature of 320 °C and pressure of 25 [|MPa] to become amorphous in water. [|[14]] Several different crystalline structures of cellulose are known, corresponding to the location of hydrogen bonds between and within strands. Natural cellulose is cellulose I, with structures Iα and Iβ. Cellulose produced by bacteria and algae is enriched in Iα while cellulose of higher plants consists mainly of Iβ. Cellulose in regenerated cellulose fibers is cellulose II. The conversion of cellulose I to cellulose II is irreversible, suggesting that cellulose I is [|metastable] and cellulose II is stable. With various chemical treatments it is possible to produce the structures cellulose III and cellulose IV. [|[15]] Many properties of cellulose depend on its chain length or [|degree of polymerization], the number of glucose units that make up one polymer molecule. Cellulose from wood pulp has typical chain lengths between 300 and 1700 units; cotton and other plant fibers as well as bacterial cellulose have chain lengths ranging from 800 to 10,000 units. [|[10]] Molecules with very small chain length resulting from the breakdown of cellulose are known as [|cellodextrins] ; in contrast to long-chain cellulose, cellodextrins are typically soluble in water and organic solvents. Plant-derived cellulose is usually found in a mixture with [|hemicellulose], [|lignin] , [|pectin] and other substances, while [|microbial cellulose] is quite pure, has a much higher water content, and consists of long chains. Cellulose is soluble in [|cupriethylenediamine] (CED), [|cadmiumethylenediamine] (Cadoxen), [|//N//-methylmorpholine //N//-oxide] and [|lithium chloride] / [|dimethylformamide]. [|[16]] This is used in the production of regenerated celluloses (as [|viscose] and [|cellophane] ) from [|dissolving pulp].

Breakdown (cellulolysis)
Cellulolysis is the process of breaking down cellulose into smaller polysaccharides called [|cellodextrins] or completely into glucose units; this is a [|hydrolysis] reaction. Because cellulose molecules bind strongly to each other, cellulolysis is relatively difficult compared to the breakdown of other polysaccharides. [|[20]] Processes do exist however for the breakdown of cellulose such as the Lyocell process [|[21]] which uses a combination of heated water and [|acetone] to break down the cellulose strands. Most mammals have only very limited ability to digest dietary fibres such as cellulose. Some [|ruminants] like cows and sheep contain certain [|symbiotic] [|anaerobic] bacteria (like// [|Cellulomonas] //) in the flora of the rumen, and these bacteria produce [|enzymes] called [|cellulases] that help the microorganism to break down cellulose; the breakdown products are then used by the bacteria for proliferation. The bacterial mass is later digested by the ruminant in its digestive system (stomach and small intestine). Similarly, lower [|termites] contain in their [|hindguts] certain [|flagellate] [|protozoa] which produce such enzymes; higher termites contain bacteria for the job. Some termites may also produce cellulase of their own. [|[22]] [|Fungi], which in nature are responsible for recycling of nutrients, are also able to break down cellulose. The enzymes utilized to [|cleave] the [|glycosidic linkage] in cellulose are [|glycoside hydrolases] including endo-acting [|cellulases] and exo-acting [|glucosidases]. Such enzymes are usually secreted as part of multienzyme complexes that may include [|dockerins] and [|carbohydrate-binding modules]. [|[23]]