Glycolysis?

Question

1. At what metabolic step are the reactants of glycolysis considered doubled?

2. What is the phosphoryl donor for the carbon-1 and carbon-6 of fructose- 1,6-bisphosphate?

Answer 1

The cleavage of fructose 1,6 bisphosphate by aldolase b  generates two 3 carbon fragments which are inequilibriul via triose isomerase.(dihydroxyacetone -phosphate to glycerol-phosphate, and glyceraldehyde -3 phosphate). As glyceraldehyde -3 P is used in the next step and converted to 1, 3 bisphosphoglycerate..then more dHAP shifts toward glyceraldehyde -3P because of LeChatelier's principle ( the delta G for the reaction is very close to zero ) . So theoretically you have two glyceraldehyde-3 Ps instead of one so all reactions past aldolase one doubles the yields...This is why 2 ATPs are invested ( hexokinase  and phosphofructokinase ) but 4 are made ( post aldolase)for a net yield of 2 ATPs.  The phosphate donor is ATP the 6 phosphate is part of fructose-6P made frpm glucose -6-P which came from action of hexokinase on glucose .The rate limting enzyme of glycolysis , phosphofructokinase uses another ATP to phosphorylate fructose 6-P to the 1, 6 bis P

Answer 2

http://www.ncbi.nlm.nih.gov/books/bv.fcg...

1. step 4.

2. ATP