Here we are starting a new series of lessons for those preparing for the position of assistants at various companies, corporations or universities.

Science and technology

Carbohydrates are some of the most abundantly occurring substances in nature. In the presence of sunlight, plants can manufacture carbohydrates through a process called photosynthesis. Carbohydrates are the principal component of human diets all over the world. They are the most important source of energy for humans.

Saccharides is the chemical name of carbohydrates. A saccharide group consists of carbon, hydrogen and oxygen in the ratio 1: 2: 1. Depending upon the number of saccharide groups in them, carbohydrates can be monosaccharides, disaccharides and polysaccharides.

The simplest form of carbohydrates are monosaccharides. They cannot be converted into simpler compounds through hydrolysis. Glucose, fructose and galactose are examples of monosaccharides with nutritional value.
Glucose is also called dextrose or grape sugar. It is the principal source of energy for our body as it can be easily digested and absorbed. Sweet fruits, honey and certain vegetables like carrots, sweet corns and onions are abundant sources of glucose.

Fructose is sweeter than glucose. It is also called levulose or fruit sugar. Fructose is found in honey and ripe fruits. It is easily absorbed by the body.

Galactose is not freely available in nature. Compounds consisting of galactose and another monosaccharides are widely available. Lactose, which is the form of sugar, present in milk is a compound of glucose and galactose.

Disaccharides are formed when two monosaccharides combine with the elimination of one molecule of water. digestive enzymes can split them into simpler sugars that can be absorbed by the body. Acid hydrolysis is another process through which disaccharides can be split. Sucrose, lactose and maltose are disaccharides of nutritional value.

Sucrose also called invert sugar is the common form of sugar in our diet. When glucose and fructose combine with the elimination of one molecule of water, we get sucrose. Sucrose has much commercial value and is manufactured on a large scale from sugar cane and beetroot.

Maltose or malt sugar is formed when two molecules of glucose combine with the elimination of one molecule of water. It is the sugar formed in cereal grains during germination.

Lactose also known as milk sugar is found in the milk of mammals. It is formed when glucose and galactose combine with the elimination of one molecule of water.

When several monosaccharides combine, we get polysaccharides. The majority of them are insoluble or only slightly soluble in water. Starch, dextrins, glycogen and dietary fibres are polysaccharides of nutritional importance.

When several hundreds of glucose units combine together, we get a complex structure called starch. Starch is found in plants. cereals, millets, roots and tubers.

When starch breaks down to maltose during the process of digestion, a substance called dextrin is also formed. Dextrins are also formed during the germination of seeds.

Glycogen is also called animal starch. It is found in the liver and muscles of animals and humans. In order for the body to use the glycogen, it has to be converted back to glucose. Glycogen is formed when a large number of glucose molecules condense.