Biochemistry Biochemists study the chemistry of life. Living things exhibit a large varitey of activities: eating; sleeping; moving; talking; thinking . The unique chemical reactions behind these activities are due to biomolecules which contain specific functional groups. A functional group is a group of atoms within a molecule, which makes it react in a certain way - gives it its chemical character. Biological molecules often have more than one functional group.

Carbohydrates Carbohydrates all contain the alcohol group: Some also contain an aldehyde group:  Carbohydrates can be divided into three classes: Monosaccharides, e.g. Glucose - simple sugar molecules Disaccharides, e.g. Sucrose - two simple sugar molecules joined together Polysaccharides, e.g. Starch and Cellulose - large macro molecules made up of many simple sugar units Glucose  Glucose is used by the body when energy is needed, and is converted to carbon dioxide and water inside living cells. Any excess glucose is converted by enzymes into a polysaccharide, glycogen, which is stored in the body. Sucrose Sucrose, a disaccharide, is converted to a monosaccharide before it can be utilised by the body and absorbed through the intestinal wall. Starch Starch is a polysaccharide formed through the condensation polymerisation of a glucose monomer. It is broken down by the enzyme amylase into glucose for use by the body. Starch is the main constituent of flour, found in cereals and some vegetable foods (rice is 75% starch, corn is 50% starch, potatoes are 20% starch).

Bibliography Martin, D. & Sampugna, J. Molecules in Living Systems (New York: Harper & Row, 1973).