Re: what are some of the chemical nature & variety of carbohydrate

Carbohydrates are the most abundant organic compounds in the plant world.  
They are all compounds of carbon, hydrogen and oxygen and differ in the 
number and bonding arrangement of these atoms.  Carbohydrates have many 
biological roles; among them are the storage of chemical energy (glucose, 
starch, and glycogen) and forming the structural components of plants 
(cellulose).  

The simplest members of the carbohydrate family are called saccharides, 
from the Latin word for sugar, saccharum.  These compounds have sweet 
tastes; glucose is an example.  Most carbohydrates have two or more 
saccharide units chemically linked together.  Some familiar examples of 
these are lactose, which is the main sugar present in milk.  This compound 
is formed by linking a molecule of glucose and of galactose.  Sucrose 
(table sugar) is the most abundant disaccharide in the biological world, 
and is obtained mainly from sugar cane and from sugar beets.  Sucrose is a 
disacharide comprised of glucose and fructose.

Cellulose is a widely distributed polysaccharide, which makes up the cell 
wall material in wood and is the key plant skeletal compound.  Cellulose is 
a polymer formed from a large number of glucose units.  Cellulose fibers 
consist of bundles of parallel polysaccharide chains held together by 
hydrogen bonds between the chains.  This arrangement of the molecular 
chains in bundles gives cellulose its high mechanical strength.

There are a tremendous variety of carbohydrates in nature; any basic 
chemistry or biology book will suffice to introduce you to the great 
variety of these compounds and their importance in the biological world.