Yeast growth rate on galactose vs glucose

[Peter haggie]

Dear Yeast People

This retes to an old problem from 1996 that wasn't resolved as I could see. 

Why do yeast grow more slowly on galactose than glucose?

Entry of gal is into glycolysis at the G-6-P stage

gal -> gal-1-P -> glu-1-P -> glu-6-P etc

This uses no more ATP than glucose entry (by my calculation) and so why does
gal mean that growth is so slow.  Further, I ave been told that gal results
in cells that need to be respiring, ie thay do not produce ethanol.  Any ideas.

I've tried lit searches, the Fraenkel revview and I am presently looking for
a new book called Carbohydrate metabolism with a chapter on yeast by Gancedo.

Any ideas?

Yours 

Pete Haggie