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Biology - Carbhoydrates

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Introduction

The Structure and Function of Carbohydrates Large biological molecules are called macromolecules, there are giant molecules (polymers) made up of repeating units (monomers). Carbohydrates are one of the main classes of biological molecules. Macromolecule units (monomers) are joined together by condensation reactions and hydrolysis reactions split macromolecules down into their individual units. Carbohydrates are molecules that contain elements of carbon, hydrogen, and oxygen. Carbohydrates have a 2:1 hydrogen to oxygen ratio, there are twice as many hydrogen atoms as oxygen atoms (the same proportion as in water). Carbohydrates are categorised in three many groups: > Monosaccharide - monomers and therefore contain single surgar. > Disaccharide - contain double sugars. > Polysaccharide - are large molecules containing many complex sugars. ...read more.

Middle

These are shown below: ?-glucose: �-glucose: Galatose: Fructose: The main function of monosaccharide is that they are able to move through bodies, gut walls and therefore important as a source of energy. All other carbohydrates have to be converted to monosaccharides before energy can be released and its is due to it's small size they are very soluble and it is the form of monosaccharides that all carbohydrates are carried in the blood. Disaccharides are double sugar molecules. Two monomers like ?-glucose molecules can be joined together to form a disaccharides (maltose). The bond forms between carbon 1 of one ?-glucose molecule and carbon 4 of the other and is called a glycoside bond. ...read more.

Conclusion

Starch is a mixture of two compounds (amylase and amylopectin). Both of these molecules are polymers containing a large but variable number of ?-glucose molecules linked to each other by condensation. Glycogen is stored in the liver and muscles it is similar to amylopectin but with more frequent branches. Starch and glycogen are efficient storage molecules because they are compact and can be stored in relatively small spaces and is also easily broken down to glucose when need for respiration. They are both insoluble allowing no osmotic influence on the cell and do not lower water potential therefore will not be able to diffuse out of the cell. Cellulose is structural and forms an important part of plant cells walls. The monomer that forms cellulose is �-glucose. They are unbranched polymers of glucose. ...read more.

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