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Why is glucose classified as an aldohexose?

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A biochemical flowchart shows the metabolic pathways for carbohydrate utilization, including glycolysis, the pentose phosphate pathway, and the tricarboxylic acid (TCA) cycle. The diagram traces the conversion of glucose, fructose, and glycerol through various intermediates, leading to energy production, carbon dioxide release, and biosynthesis of amino acids and porphyrins. Key steps and branches are labeled, with colored boxes highlighting biosynthetic outputs. — Carbohydrate Pathways for the utilization of carbohydrates.

Glucose is classified as an aldohexose because of its specific chemical structure and composition. The term is derived from two key characteristics of the monosaccharide molecule:1

Hexose: This indicates that the molecule contains six carbon atoms.1
Aldo-: This signifies that the molecule contains a chemically reactive aldehyde group.1

In biochemistry, monosaccharides are categorized based on the number of carbon atoms they possess and the type of reactive group they contain. Because glucose consists of a six-carbon chain and features an aldehyde group, it is defined as an aldohexose.1