Tetrose

Definition
noun, plural: tetroses
A four-carbon monosaccharide
Supplement
Monosaccharides are the simplest form of carbohydrates. They are classified according to the number of carbon atoms in a monosaccharide. In particular, a tetrose is a monosaccharide with four carbon atoms. Monosaccharides may also be classified based on the type of carbonyl group they contain. An aldose is a monosaccharide that contains an aldehyde group (-CHO) whereas a ketose is one that contains a ketone (C=O). Thus, an aldotetrose is a tetrose with an aldehyde group and therefore the carbonyl group is located in position 1. A ketotetrose, in contrast, is a tetrose with a ketone functional group located in position 2.
Naturally-occurring tetroses are D-erythrose, D-threose, and D-erythrulose. The erythrose, C₄H₈O₄, is a tetrose with one aldehyde group. It was first isolated by French pharmacist Louis Feux Joseph Garot in 1849. The erythrose 4-phosphate is a metabolite in the Calvin cycle and in the pentose phosphate pathway. Threose is a tetrose and an enantiomer of erythrose. Another enantiomer is erythrulose. It has the same chemical formula: C₄H₈O₄. Nevertheless, the erythrulose is a ketotetrose for having a ketone group in its structure.
Word origin: tetr(a)– (“four”) + –ose (relating to sugars)
See also:

• monosaccharide
• carbohydrate
• aldose
• ketose