Cellulose: Difference between revisions
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= Structure and Function = | === Structure and Function === | ||
Cellulose is an unbranched polymer of [[Beta-glucose|beta-glucose]]. The linkages are called beta-1,4-glycosidic bonds, formed between adjacent [[Glucose|glucose]] monomers undergoing [[Condensation reaction|condensation reactions]]. This polymer forms long, straight chains giving it a rigid structure. Because [[Hydrogen bonds|hydrogen bonds are]] formed between parallel chains, cellulose forms [[Microfibrils|microfibrils]]. <ref>Berg J., Tymoczko J and Stryer L., 2007. Biochemistry. 7th edition. New York: WH Freeman</ref> Around 40 cellulose chains combine together, by forming hydrogen bonds, to form a microfibril. <ref>Bruce Alberts et al, 2007. Molecular Biology of the Cell. 5th edition. USA: Garland Publishing Inc.</ref> Thus, cellulose is a major component of plant cell walls, giving the cell tensile strength | Cellulose is an unbranched polymer of [[Beta-glucose|beta-glucose]]. It is among the most abundant organic compounds in the biosphere. The linkages are called beta-1,4-glycosidic bonds, formed between adjacent D-[[Glucose|glucose]] monomers undergoing [[Condensation reaction|condensation reactions]]. This polymer forms long, straight chains giving it a rigid structure. Because [[Hydrogen bonds|hydrogen bonds are]] formed between parallel chains, cellulose forms [[Microfibrils|microfibrils]]. <ref>Berg J., Tymoczko J and Stryer L., 2007. Biochemistry. 7th edition. New York: WH Freeman</ref> Around 40 cellulose chains combine together, by forming hydrogen bonds, to form a microfibril. <ref>Bruce Alberts et al, 2007. Molecular Biology of the Cell. 5th edition. USA: Garland Publishing Inc.</ref> Thus, cellulose is a major component of plant cell walls, giving the cell tensile strength <ref>Berg J., Tymoczko J and Stryer L., 2007. Biochemistry. 7th edition. New York: WH Freeman</ref>. | ||
< | Plant cells have a very negative water potential, due to many different solutes dissolved within the cytosol. Water, therefore, enters cells from the outside. The cellulose [[Cell wall|cell wall]], however, prevents osmotic lysis; in this state, plant cells are said to be turgid. Turgor pressure is very important for the mechanical rigidity of the cell, and is also vital for expansion during cell growth <ref>Bruce Alberts et al, 2007. Molecular Biology of the Cell. 5th edition. USA: Garland Publishing Inc.</ref>. | ||
=== Diet === | |||
< | Mammals do not have the cellulases required to digest cellulose and therefore cannot digest vegetable fibres and wood. However, cellulose is an important dietary factor as a fibre component. Insoluble fibres such as cellulose increase the rate that food travels through the large intestine which minimises the exposure of toxins in the diet <ref>Berg J., Tymoczko J., Stryer L., 2007. Biochemistry. 7th edition. New York: WH Freeman</ref>. | ||
=== References === | |||
= References = | |||
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Latest revision as of 04:35, 17 November 2013
Structure and Function
Cellulose is an unbranched polymer of beta-glucose. It is among the most abundant organic compounds in the biosphere. The linkages are called beta-1,4-glycosidic bonds, formed between adjacent D-glucose monomers undergoing condensation reactions. This polymer forms long, straight chains giving it a rigid structure. Because hydrogen bonds are formed between parallel chains, cellulose forms microfibrils. [1] Around 40 cellulose chains combine together, by forming hydrogen bonds, to form a microfibril. [2] Thus, cellulose is a major component of plant cell walls, giving the cell tensile strength [3].
Plant cells have a very negative water potential, due to many different solutes dissolved within the cytosol. Water, therefore, enters cells from the outside. The cellulose cell wall, however, prevents osmotic lysis; in this state, plant cells are said to be turgid. Turgor pressure is very important for the mechanical rigidity of the cell, and is also vital for expansion during cell growth [4].
Diet
Mammals do not have the cellulases required to digest cellulose and therefore cannot digest vegetable fibres and wood. However, cellulose is an important dietary factor as a fibre component. Insoluble fibres such as cellulose increase the rate that food travels through the large intestine which minimises the exposure of toxins in the diet [5].
References
- ↑ Berg J., Tymoczko J and Stryer L., 2007. Biochemistry. 7th edition. New York: WH Freeman
- ↑ Bruce Alberts et al, 2007. Molecular Biology of the Cell. 5th edition. USA: Garland Publishing Inc.
- ↑ Berg J., Tymoczko J and Stryer L., 2007. Biochemistry. 7th edition. New York: WH Freeman
- ↑ Bruce Alberts et al, 2007. Molecular Biology of the Cell. 5th edition. USA: Garland Publishing Inc.
- ↑ Berg J., Tymoczko J., Stryer L., 2007. Biochemistry. 7th edition. New York: WH Freeman