The standard free energy change of phosphate hydrolysis is shown below for sever

Question

The standard free energy change of phosphate hydrolysis is shown below for several molecules in the glycolytic pathway.

Which statement explains why glucose phosphorylation could not occur without ATP investment?
A.   Without ATP investment in stage I of glycolysis, the concentration of ATP would become too high and would inhibit phosphofructokinase, leading to inhibition of the entire glycolytic pathway.

B.   Without ATP investment, glucose would not become "trapped" in the cell and could easily be transported out as blood glucose levels decrease. This transport would reduce the amount of glucose available for some organs.

C.   Without ATP investment it would be impossible to regulate the entry of glucose into glycolysis.

D.   Without ATP investment, one or both of the substrates would need to exceed the solvent capacity of the cell for glucose phosphorylation to occur.

Molecule G (kJ/mol) Phosphoenolpyruvate 61.9 1,3-Bisphosphoglycerate 49.4 ATP ADP + Pi 30.5 Fructose-6-phosphate 15.9 Glucose-6-phosphate 13.8

Explanation / Answer

ATP provides glucose with high energy phosphate group. It converts glucose to Glucose-6-phosphate which is more reactive form of glucose and phosphate group is required by glucose in order to enter in glycolytic pathway.

Without ATP investment, no phosphate group will be provided to glucose molecule making it impossible for glucose to enter in glycolysis.

So stament C explains why glucose phosphorylation cannot happen without ATP investment.

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