Definition

Noun: A ketose is any monosaccharide sugar whose molecule contains a ketone group (C=O) or its cyclic hemiacetal form. This distinguishes it from an aldose, which contains an aldehyde group.

Usage

Ketoses are a fundamental class of simple sugars in biochemistry. The term is used to classify sugars based on their carbonyl functional group. * Fructose is a common ketose found in fruits and honey. * In metabolism, the ketose ribulose is an important intermediate in the Calvin cycle. * Biochemists test for ketoses using specific chemical reactions like Seliwanoff's test.

Advanced Usage

• Structural Isomerism: A ketose and an aldose with the same number of carbon atoms (e.g., fructose and glucose) are functional group isomers.
• Tautomerization: In solution, ketoses can exist in equilibrium between their open-chain ketone form and cyclic furanose or pyranose hemiacetal forms.

Variants and Related Words

• Ketosis (n): A metabolic state characterized by elevated levels of ketone bodies in the blood, not directly related to dietary ketose sugars.
• Aldose (n): The complementary class of monosaccharides containing an aldehyde group.
• Triose, Tetrose, Pentose, Hexose: Terms that classify monosaccharides by the number of carbon atoms (e.g., a "ketohexose" like fructose).

Synonyms

• Keto sugar
• Monosaccharide ketone

Related Phrases

• Reducing sugar: Most ketoses are reducing sugars due to the presence of a potentially free anomeric carbon in their hemiacetal form.
• Keto-enol tautomerism: The chemical equilibrium relevant to the structure of ketoses.

Noun

1. any monosaccharide sugar that contains a ketone group or its hemiacetal