Ketoses are a type of simple sugar, or monosaccharide, that contain a ketone group in their molecular structure. They are characterized by having a carbonyl group (C=O) located at the second carbon atom, which distinguishes them from aldoses, another category of monosaccharides that have an aldehyde group. Common examples of ketoses include fructose and ribulose. Ketoses play important roles in various biological processes, including energy production and metabolism. They can be found in many fruits and vegetables, contributing to their sweetness. Additionally, ketoses can be converted into other sugars and compounds through metabolic pathways, making them essential for cellular functions.