Carbohydrate I

·      Term Carbohydrate is derived from French term hydrate de Carbone means

Hydrate of Carbon.

·        Basically carbohydrates are Polyhydroxy Aldoses or Ketoses and their condensation products.

o   Aldoses – (-CHO) group at one end. E.g.- Glucose, Glactose

o   Ketoses – (=C=O) group in the chain. E.g. – Fructose, Ribulose

·        Many small carbohydrates are sweet in test so they are called Sugar or Saccharide.

 Monosaccharide

·    Simplest carbohydrate

·        Cannot be hydrolyzed into smaller carbohydrate

·        General Formula C_nH_2nO_n

      On the basis of number of carbon atoms monosaccharides  can be classified into following groups :-

·        

Structure of some Important Monosaccharides

Glyceraldehyde & Dihydroxyacetone

Ribose & Deoxyribose

Glucose

·        Blood sugar

·        Grape sugar

Fructose  

·        Sweetest of all natural sugars

·        Fruit sugar except Grape, Found in honey as levulose

     

  

Ring forms

·        Pyranose – 6 membered ring containing 5C and 1O atoms

·        Furanose – 5 membered ring containing 4C and 1O atoms

α and β forms

·                                                α form – (-OH ) group of C atom nearer to oxygen is downward

·                                                β form – (-OH) group of C atom nearer to oxygen is upward

D and L form

·        D form – Dextro(right) rotation of light after passing through the carbohydrate solution

·                   L form – Laevo (left) rotation of light after passing through the carbohydrate solution

§  D form is more common in living world

Derived Monosaccharide

Those compounds which are formed after addition or deletion of atom or group of atoms are subjected in this group.

On the basis of added or deleted entity derived monosaccharides are placed in following groups:- 

·        Deoxy sugar – Formed after deletion of one oxygen from any monosaccharide. E.g. – Deoxyribose sugar

·       

           Sugar Acid – Formed after oxidation of the monosaccharide. E.g. – Glucuronic Acid

   Amino Sugar – (-NH₂) group get attached with the monosaccharide. E.g. - Glucosamine

Sugar Alcohol – Formed after addition of (-OH) group with monosaccharide. E.g.- Sorbitol

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