Notes, Exercises, Videos, Tests and Things to Remember on Structure of Glucose and Fructose and Functions of carbohydrates
Please scroll down to get to the study materials.
Glucose and fructose are monosaccharides. There is water soluble and sweet in the test. Their general molecular formula is C6H12O6 and both are functional isomers. Open chain and cycle structures are assigned to them. Some properties are explained by open-chain structure whereas some other properties are explained by the cyclic structure.
The symbols D and (+) represent the configuration and optical rotation of the molecule respectively. The form of glucose in which the –OH group at C-5, i.e. farthest asymmetric carbon atom from carboxyl carbon, lies on the right, is called as D-glucose and if it lies on the left, the form is called as L-glucose. Glucose is an optically active compound as it possesses four asymmetric carbon atoms or the chiral centers. It may possess two optical isomers, one which rotates the plane-polarized light to the right is called as dextrorotatory and the another which rotates the plane of polarized light to the left is called as levorotatory glucose. Naturally occurring glucose is isomer with D-configuration. Its mirror image will be (-) isomer with L-configuration. Such mirror image isomers are known as enantiomers. The (+) and (-) isomers of glucose are thus enantiomers. If the amount of these isomers is equal, the resulting mixture is called as the racemic mixture. The net optical rotation of a racemic mixture becomes zero.
Naturally occurring fructose is (-) isomer with D-configuration. Its mirror image will be (+) isomer with L-configuration. The L (+) from either exists in minor amount along with D (-) from or is synthesized through various chemical reactions. The (+) form is a mirror image to (-) from and hence both are enantiomers. The position or the arrangement of –OH group at c-5 determines whether the configuration is D or L and the action of the isomer on the plane polarized light determines whether the isomer is (+) or (-).
Carbohydrates constitute a principal class of organic compounds for living beings. The lives can not be assumed without carbohydrates. Some of the major functions of carbohydrates in living organisms are given below:
Bahl, B S, Bahl, and Arun. Advanced Organic chemistry. S. Chand and company Ltd., n.d.
Sthapit, M K, R R Pradhananga, and K B Bajracharya. Foundations of chemistry. Taleju Prakashan, n.d.
Tewari, K S, S N Mehrotra, and N K Vishnoi. A textbook of organic chemistry. Vikash publishing House Pvt. ltd., n.d.
Verma, N K and S K Khanna. Compressive chemistry. 8th edition. Laxmi publications P. Ltd., 1999.