The free energy change of hydrolysis of sucrose into glucose and fructose is ΔG = - 7
kcal/mol. When the enzyme sucrase is added to the reaction mixture, what happens to the ΔG of the reaction?

Question

BlackTom AI · Accepted Answer

Consider the thermodynamics of a chemical reaction. The given ΔG for hydrolysis of sucrose to glucose and fructose is a fixed value under the specified conditions.
Option a: 'The ΔG is decreased' would imply that the free energy change becomes more favorable by reducing ΔG, which is not how enzymes operate. Enzymes accelerate the rate without altering the thermodynamic balance of reactants and products.
Option b: 'The ΔG is increased' would imply the reaction becomes less favorable thermodynamically, which again is not caused by enzyme action; enzymes do not change the inherent ΔG of a reaction.
Option c: 'The ΔG remains the same' correctly states that the free energy change is determined by the intrinsic thermodynamics of the reactants and products and remains unchanged by catalysis. Enzymes lower the activation barrier and speed up the rate, but not the overall ΔG.
Option d: 'The ΔG is equal to the activation energy of sucrase' confuses ΔG with the activation energy barrier. Activation energy is a kinetic parameter that enzymes reduce to accelerate the reaction; it is not the same as ΔG, which is a thermodynamic quantity for the overall reaction.
In summary, enzymes influence how fast a reaction proceeds (rate) by lowering the activation energy, while the overall free energy change ΔG of the reaction remains constant. Therefore, the correct interpretation is that the ΔG remains the same.

The free energy change of hydrolysis of sucrose into glucose and fructose is ΔG = - 7 kcal/mol. When the enzyme sucrase is added to the reaction mixture, what happens to the ΔG of the reaction?

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