Question on fructose and anaerobic respiration in yeast

I know that as glucose and fructose are monomers they can be used by yeast for anaerobc respiration more easily than larger carbohydrate molecules.
However, i read somewhere (and i can't remember where) that before fructose can be used it has to be convertd into glucose. Is this true, and if so, how is it converted into glucose and what by?

Really would appreciate some help!

Reply 1

-Kav-

To the best of my knowledge, only glucose can undergo glycolysis. As such, the most likely suspect is emzyme activity in the digestive tract. I'm not entirely sure, though.

Reply 2

Comp_Genius

Well fructose can be phosphorylated to fructose-1-phosphate which in turn is converted to glyceraldehyde and glycerone phosphate. both can then enter the glycolytic pathway.

Reply 3

alispam

Yes fructose must be converted into glucose or fructose-1-phosphate to enter glycolysis. However most yeast can do this due to evolving on fruit (containing lots of fructose) so they have developed the necessary enzymes. Hence these yeasts can't use lactose (or galactose) - molecules of a similar shape and composition- as these are contained in milk which the yeast does not come into contact with.