Fructose (which is also known as fructopyranose) means, literally, "fruit sugar". It is a very sweet six-carbon sugar that serves as a building block for more complex sugars and carbohydrates. It is found naturally in fruits and some vegetables and is used widely in the food industry because it is sweeter than sucrose.

Fructose 1,6-bisphosphate is a key glycolysis intermediate (it is classified as a hexose diphosphate). It was discovered by Arthur Harden and William Young in 1905. In the third step of glycolysis, fructose 6-phosphate and ATP are converted to fructose 1,6-bisphosphate and ADP with the aid of phosphofructokinase. In step 4, fructose 1,6 bisphosphate (with the aid of aldolase) is cleaved into dihydroxyacetone phosphate and glyceraldehyde 3-phosphate.

From the science dictionary at

From "The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, Tenth Edition (1983)",:

4149. Fructose. D-fructose; B-D-fructose; levulose; fruit
sugar; Fructoseril; Laevoral; Levugen; Vaevosan; C6H12O6, mol wt
108.16. C 40.00%, H 6.72%, O 53.29%. Occurs in a large number of
fruits, honey, and as the sole sugar in bull and human semen.

Fructose is reported to be present in human semen in excess of 1.2 g/L, and no, they did not collect a litre of semen! Fructose, like most starches, has about 4 kcal/g of energy. The average human ejaculation contains 3.5 mL of semen. Therefore, the average ejaculation has 16.8 calories from fructose. However, semen also contains sperm cells and protein, which would need to be measured to get a truly accurate energy rating.

I would like to point out at this time that 1 calorie is defined as the amount of energy required to raise 1 gramme of water 1 degree centigrade. Food contains a lot of energy. So most scientists use the kilocalorie for measuring food. Common people don't like big words, so they just call it a Calorie, capitalised to differentiate between the two.

Fruc*tose" (?), n. [L. fructus fruit.] Chem.

Fruit sugar; levulose.



© Webster 1913.

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