CARBOHYDRATES
Carbohydrates are polyhydroxy aldehydes or ketones, or complex substances which on hydrolysis produce polyhydroxy aldehyde or ketone subunits.
Three major groups' of Carbohydrates are: Monosaccharides, Oligosaccharides & Polysaccharides.
General formula for Carbohydrates is Cx(H2O)y.
Monosaccharides:
These are generally Trioses, Tetroses, Pentoses. Hexoses & Heptoses. General formula for monosaccharides is (CH2O)n.
Examples of trioses are dihydroxy acetone and glyceraldehydes. These are also intermediates in respiration and photosynthesis. Examples of Hexose", Glucose, Galactose, Fructose etc.
Oligosaccharides: These have 2-10 Monosaccharides. General formula of oligosaccharides is Cx(H2O)y.
If two Monosaccharides then it is a Disaccharide. Examples of Disaccharides are: Maltose, Lactose and Sucrose etc. Dextrins are the oligosacchride containing 3-10 Monosacchrides
Polysaccharides: These have more than ten Monosaccharides. General formula of polysaccharides is Cx(H2O)y –.
Examples arc' Cellulose, Starches and Glycogen etc. Most abundant polysaccharide is Cellulose. Polysaccharides are usually branched. Cellulose present in wood, cotton and paper. Starches present in cereals and root tubers etc. In biology the most important hexose is glucose. Our blood normally contains 10.08 % glucose. For the synthesis of 10 g of glucose 717.6 Kcal of solar energy is used. Cellulase is secreted by bacteria, yeasts and protozoa.
1)- STARCH:
Starch is compact, insoluble and it is a mixture of two compounds, amylase and amlyopectin.
Amylose is an un-branched polymer in which glucose monomers are joined by α-1 4-glycosidic linkages. They are soluble in hot-water.
Amylopectin molecule α-1, 4-glycosidic linkages and α-1, 6-glycosidic linkages. This allows branching. They arc "Insoluble in hot or cold water.
2)- GLYCOGEN:
In humans, glycogen is the main storage carbohydrate. Its structure is similar to amylopectin, but it is even more frequently branched.
In humans, glycogen is stored in large amounts in the liver and the muscles. During prolonged exercise, when the immediate supply of glucose is used up, the body restores its supplies by breaking down glycogen.
If an average person goes without food, his or her glycogen stores last for about a day. When glycogen runs out, the body turns to using its lipid store. This is why eating lesswhile taking more exercise is the quicker way to lose weight.
One of the major changes associated with improving fitness is an increase in the amount of the enzyme glycogen synthetase in the muscles. This allows glycogen to be built up faster after it has been used.
3)- CELLULOSE:
Cellulose is a structural polysaccharide. It gives strength and rigidity to plant cell walls.
Individual cellulose molecules are long un-branched chains containing many β-1, 4-glycosidic linkage. The molecules are straight, side by side and are called microfibrils.
Cellulose is probably the most abundant structural chemical on Earth but few animals can digest it because they do not make the necessary enzyme, cellulase. Herbivorous animals, whose diet contains large amounts of cellulose, can deal with it because they have cellulase-producing microorganisms in their digestive system.