Glucose is a six-carbon sugar, also known as a monosaccharide. It is essential for a variety of chemical reactions. Plants create glucose in the process of photosynthesis, and humans use glucose to create cellular energy.
Chemical Formula
The chemical formula of glucose is C6H12O6. This means that there are six carbon atoms, 12 hydrogen atoms and six oxygen atoms for every molecule of glucose.
Straight Chain Structure
In the straight-chain form of the molecule, glucose carbon molecules are attached to each other in a straight line. These carbons are numbered from 1 to 6, and the first carbon atom is attached to an aldehyde group, making this sugar an aldose sugar.
Ring Form
In solution, the glucose molecule primarily exists as a ring structure, which is formed when the hydroxyl OH group on the sixth carbon atom reacts with the aldehyde group on the first carbon atom. This ring contains five carbon atoms and one oxygen atom.
Types
Glucose can exist as either one of two stereoisomers in the ring form. When the hydroxyl groups on the first carbon atom is in the same plane as the hydroxyl group on the second carbon atom, it is the alpha form. When the hydroxyl group on the first and third carbon atoms are in the same plane, it is the beta-form of glucose.
L-Glucose
Naturally occurring glucose exists in the D-form. However, there is also an L-form, which is the mirror image of the D-form. "D" is for "dextrorotatory," meaning right-rotating, as solutions of D-glucose rotate light to the right. In contrast, the "L" is for "levorotatory," or left-rotating, as solutions of L-glucose rotate light to the left.
