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Saccharides - Structure and Function.

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Introduction

Saccharides - Structure and Function Saccharides are what we commonly know as sugars, The are composed of carbon, Hydrogen and oxygen and are used in the body for everything from the manufacture of DNA to respiration in cells. What they are used for Carbohydrates' main function in the body is in respiration, a process without which living creatures could not exist, they are perfect for this job as they oxidize very easily. Only 10% of any sugar can be active or in straight chain form at any one time, the other 90% of the sugars are tied up in a circular form of the sugar which ties up the active group of the sugar, hence preventing it from reacting. H Glucose in straight chain form - C=O H-C-OH OH-C-H H-C-OH H-C-OH CH2OH Glucose in ring form - Active groups All sugars contain one of two active groups ...read more.

Middle

For example Glucose - C6H12O6 and Fructose - C5H10O5. Both of these conform to the formula (CH2O)n. Monosaccharides can be classed as trioses, tetroses, pentoses, and heptoses depending on the number of carbon atoms there are in the molecule. Their specific molecular formulas changes depending on the no. of carbon atoms they contain, but they still conform to the general formula (CH2O)n. All monosaccharides are sweet to taste and are soluble in water. Uses of different Monosaccharides Trioses : Are involved mainly in carbohydrate metabolism Pentoses : Are used in the synthesis of nucleic (DNA/RNA) acids, Synthesis of ATP (energy molecules),are CO2 acceptors in photosynthesis. Hexoses: Used as respiratory substrates (e.g. glucose), used in the synthesis of di./poly. saccharides Condensation Polymerization Monomers can be joined together in chains to form larger polysaccharides this can be done by condensation polymerization. ...read more.

Conclusion

Polysaccharides are generally not sweet or soluble. The most common forms of polysaccharides we know are starch and glycogen, both almost identical to each other. Starch is used as an energy store molecule in plants and glycogen in animals is used for the same purpose. Polysaccharides are used as storage molecules because of the fact that they are so large they are insoluble and they can coil/fold into compact shapes, they are also used as structural molecules (cellulose). Tests for Saccharides The most common test for reducing sugars (all mono/disaccharides except sucrose) is The Benedicts test. This is done by adding copper sulphate to a solution of the sugar and water and then heating it gently. If the sugar is a reducing sugar it will reduce the copper sulphate and make a residue of brick red copper oxide in the solution. A common test for starch/ glycogen (polysaccharides) is to add iodine to it, suspended in water. The suspension should turn from brown to blue black. ...read more.

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