Glucose

Glucose a simple sugar monosaccharide, is one of the most important carbohydrates and is used for energy in plants and animals. It was formerly known as dextrose.

Glucose (C₆H₁₂O₆) is a hexose--a monosaccharide containing six carbon atoms. Five of these carbons, plus an oxygen atom, form a loop called a pyranose ring, the most stable form for aldoses. In this ring, each carbon is linked to hydroxide and hydrogen side groups with the exception of the fifth atom which links to a 6th carbon atom outside the ring, forming a group of CH₂OH.

The two main isomers of glucose are: alpha-glucose and beta-glucose. Structurally, they differ in the orientation of the hydroxide group linked to the second carbon in the ring. The alpha form has the hydroxide group below the other hydrogen group, the beta form has the hydroxide group above the hydrogen.

In respiration through a series of enzyme catalysed reactions, glucose reacts with oxygen to form carbon dioxide and water, giving off energy.

Chemically joined together glucose and fructose form sucrose

The older name dextrose arose because a solution of glucose will rotate polarised light towards the right. In the same vein Fructose was called levulose, a solution of levulose rotated polarised light to the left.