The structural features of carbohydrates account for the fact that a wide variety of polysaccharides exist is pentoses and hexoses. The examples of pentose are ribose, deoxyribose, ribulose and xylulose. The examples of hexose are glucose which is found in fruits, fructose which is found in milk and galactose which is found in honey. Both pentoses and hexoses are mostly found in monosaccharides. They are the most simplest sugar which cannot be futher hydrolysed into smaller units.
They contain either an aldehyde group or ketone group. They can de used to make polysaccharides, although only one type of monosaccharides is used in each type of monosaccharides. They have two types of linkage, that is 1,4 and 1,6 glycosidic bonds that are common between sugar units. Such as ? -D-glucose reacts with ? -D-glucose will produces maltose which is ? -1,4 glycosidic bonds that is common in our life. They will form more bonds between each other. Thus the branching occurs upon them.
Their lengths of chains and branches, and extent of branching can vary enormously. ? and ? forms of monosaccharides are important. These sugars may be aldose or lactose. They have many uses and importance in life. Monosaccharides are the major source of fuel for metabolism, being used both as an energy source (glucose being the most important in nature) and in biosynthesis. Such as glucose, it is very important structure in biology and almost all the living beings use glucose for the proper functioning of their body.
The energy is provided to the body by burning of glucose by the body mechanism. High chemical reactivity of sugar ( like aldehyde, keto and hydroxyl groups ) means that they are very reactive molecules. They prefer to react with other substance since with their high chemical reactivity. They will react with each other to become disaccharides, oligosaccharides and polysaccharides, such as maltose, sucrose, lactose, starch, glycogen, cellulose and chitin.