In 1906 Harden and Young, in a series of classic studies on the fermentation of
ID: 1044429 • Letter: I
Question
In 1906 Harden and Young, in a series of classic studies on the fermentation of glucose to ethanol and CO2 by extracts of brewer's yeast, made the following observations. (1) Inorganic phosphate was essential to fermentation; when the supply of phosphate was exhausted, fermentation ceased before all the glucose was used. (2) During fermentation under these conditions, ethanol, CO2, and a sugar phosphate accumulated. (3) When arsenate was substituted for phosphate, no sugar phosphate accumulated, but the fermentation proceeded until all the glucose was converted to ethanol and CO2.
Map Lehninger Principles of Biochemistry Nelson Cox SEVENTH EDITION MHE/Freeman ted by Sapling Learning In 1906 Harden and Young, in a series of classic studies on the fermentation of glucose to ethanol and CO2 by extracts of brewer's yeast, made the following observations (1) Inorganic phosphate was essential to fermentation; when the supply of phosphate was exhausted, fermentation ceased before all the glucose was used (2) During fermentation under these conditions, ethanol, CO2, and a sugar phosphate accumulated (3) When arsenate was substituted for phosphate, no sugar phosphate accumulated, but the fermentation proceeded until all the glucose was converted to ethanol and CO2 (a) s achiabgeme of glyolysis requires inorganic phosphate and therefore stops when no phosphate is available? O phosphoglycerate kinase O glyceraldehyde 3-phosphate dehydrogenase O phosphofructokinase-1 O phosphoglycerate mutase (b) What sugar phosphate accumulates under these conditions? Question continues, Scroll down O fructose 1,6-bisphosphate O glucose 1-phosphate O glucose 1,6-bisphosphate O fructose 1-phosphateExplanation / Answer
(a) Glyceraldehyde-3-phosphate dehydrogenase requires inorganic phosphate to react in step 6 of glycolysis in which the phosphate group is added to glyceraldehyde-3-phosphate to form 1,3-bisphosphoglycerate.
(b) Fructose 1,6-bisphosphate will accumulate if no inorganic phosphate is used because conversion of Fructose 6-phosphate to Fructose 1,6-bisphosphate is irreversible (step 3) and after its formation all steps are reversible, so when no inorganic phosphate is present at step 6, then the reaction will move in reverse direction and ultimately stops when there was formation of fructose 1,6-bisphosphate as from here it cannot move in backward direction and thus fructose 1,6-bisphosphate keeps on accumulating.