Chemical and Physical Properties of Sugar
Carbohydrates or sugar molecules are well known biological molecules which act as major source of energy in living bodies. They are widely distributed in plants and animals.
Many sugar molecules important structural and metabolic roles in living systems. Glucose one of the most common monosaccharide is formed during photosynthesis process in plants.
Carbon dioxide and water act as reactant in this chemical change and leads to the formation of oxygen gas with sugar molecules.
The reaction occurs in the presence of sun light and chlorophyll (a pigment in plant’s leaves).
Glucose is used in the formation of cellulose and also stored in the form of starch in plant tissues.
Animals can also synthesised carbohydrates and also use plant sources to get it.
They store the excess of sugar in the form of glycogen molecules. Most of the sugar molecules convert into glucose and absorbed by bloodstream. The conversion of sugar takes place in liver. It is major metabolic fuel of mammals and also acts as universal fuel of the fetus. It also involves in the synthesis of other sugar molecules during biological synthesis in living bodies. It stores in body in the different forms such as ribose, deoxy-ribose, galactose, and other forms.
The improper metabolism of sugar molecules can result different diseases such as diabetes mellitus, glycogen storage diseases, galactosemia, and lactose intolerance. Some of oligosaccharides can combine with proteins at all cell membranes and act as receptors which are involved in molecular recognition.
They also involve in the synthesis of antibodies and blood clotting factors. Some of sugar derivatives like heparin sulphate which is a glycoprotein take part in the adhesion of one neuron to the other.
Almost all sugar molecules are soluble in water due to tendency of the formation of H-bonding with water. They are bulky molecules alcoholic and carbonyl functional group. Two monomer units are associated with each other to form di-saccharide units.
Here monomer units are bonded together with glycosidic linkage with a condensation reaction. Glucose is a simplest sugar which shows unique physical and chemical properties. It involves in the formation of glycosides in which a sugar molecule is attached with a non-sugar moiety.
Here sugar part is known as glycone and the non-sugar part is called as aglycone.
The hydroxyl group of anomeric carbon of sugar is bonded with the hydroxyl group of non sugars such as Amygdalin. Glucose can also form Osazone with phenylhydrazine.
This is a yellowish, crystalline compound, which is formed by the sugar molecules. These sugar molecules must contain a free carbonyl group (-CHO or >C=O). One molecule of glucose can react with three molecules of phenyl hydrazine to form glucosazone.
On the contrary; sucrose cannot form same product due to absence of free carbonyl group in the molecule.
The reduction of aldose or ketose sugar leads to the formation of poly-hydroxy alcohols such as reduction of glucose results the formation of sorbitol while mannose forms mannitol and galactose reduces to dulcitol. Furctose reduces in to sorbitol and mannitol.
The oxidation of sugar molecules leads to the formation of gluconic acid, glucuronic acid, or glucaric acid.
The final product depends upon the presence of oxidising agent.