Question

In the cell, the hydrolysis of ATP (adenosine triphosphate) into ADP (adenosine diphosphate) and a phosphate group has a ΔG of -50 kJ/mol. The reaction to convert glucose and a phosphate group into glucose-6-phosphate has a positive ΔG, but can be coupled with ATP hydrolysis to produce a spontaneous reaction. What can you infer about the formation of glucose-6-phosphate?
ATP → ADP + P; ΔG = -50 kJ/mol
Glucose + P → Glucose-6-phosphate; ΔG = + ?

Answer 1

A. The ΔG of the reaction that converts glucose and a phosphate into glucose-6-phosphate has a ΔG between 0 and +50 kJ/mol.
B. The ΔG of the reaction that converts glucose and a phosphate into glucose-6-phosphate has a ΔG between 0 and -50 kJ/mol.
C. The reaction will never occur in the cell.
D. The ΔS of the reaction that converts glucose and a phosphate into glucose-6-phosphate is positive.

Answer 2

literally don't understand this at all... @Somy @aaronq @Abhisar

Answer 3

it's a coupled reaction, the energy from the hydrolysis of ATP is used to drive the phosphorylation of glucose. The gibbs free energy for the overall reaction is negative (because it's spontaneous).

Add them:

\(\sf ATP → ADP + P_i ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ΔG = -50 kJ/mol\)
\(\sf Glucose + P_i → Glucose-6-phosphate~~~~~ ΔG_2 = + ?\)

\(\sf ATP +Glucose + P_i → Glucose-6-phosphate + ADP + P\)

Add their free energy changes:

\(\sf ΔG_{overall} = -50 kJ/mol+ ΔG_2 <0\)

B) The ΔG of the reaction that converts glucose and a phosphate into glucose-6-phosphate has a ΔG between 0 and -50 kJ/mol. It must be since this is a spontaneous process.