Unit 2.1 Topic 4

 Carbohydrates 2: energy storage.

Glucose molecules contain a large number of bonds that can be broken to form simpler molecules. The breaking of glucose into simpler molecules of water and carbon dioxide in respiration releases energy. This energy can be used to make ATP, (the molecule that holds small 'packets' of energy for use in cell processes).

Respiration is often written in a word equation as:

glucose + oxygen = carbon dioxide + water + energy that is used to form ATP.

The breaking down of glucose in living organisms takes place in a series of many steps. Each step is driven by a specific enzyme. In order to be able to use glucose in respiration, an organism must have enzymes that can specifically break the glucose molecule.

Animals and plants have enzymes that break alpha-glucose only, therefore, they cannot break down beta-glucose because of its different arrangements of the H and the OH at C1, (carbon 1). This is because that enzyme function is based on shape, the overall shape of alpha-glucose is different form the of beta-glucose, meaning that while alpha-glucose can be respired, beta-glucose cannot.

Carbohydrate polymers - stores of potential energy.

Two alpha-glucose molecules bonded together form a disaccharide called maltose. The same condensation reaction can be carried out over and over, joining glucose molecules together, so forming a molecule called amylose. Amylose can consist of many thousands of glucose molecules bonded together.…