The term GLUCOSE TO FRUCTOSE is an isomer, which is a molecule that has the same chemical formula but different structural arrangements. Glucose and Fructose are two of the most common monosaccharides, or simple sugars, found in nature. They are both six-carbon molecules, but their structures differ slightly, resulting in different physical and chemical properties. Glucose is an aldohexose, meaning it has an aldehyde group at the end of its chain, while Fructose is a ketohexose, meaning it has a ketone group at the end of its chain. This difference in structure is what makes them isomers.