When glucose is combined with phosphate, what type of ΔG change is expected?

When glucose is combined with phosphate, particularly in the context of glucose phosphorylation (the addition of a phosphate group to glucose to form glucose-6-phosphate), the overall ΔG (change in Gibbs free energy) is typically considered to be negative. This process is energetically favorable, as it is often coupled with the hydrolysis of ATP, which has a large negative ΔG.

The phosphorylation of glucose serves several purposes, such as preventing the glucose from leaving the cell and facilitating its subsequent metabolism. The reaction is important in cellular respiration and in the regulation of glucose metabolism.

A positive ΔG change would indicate that the reaction is non-spontaneous in the forward direction, which does not align with the understanding of glucose phosphorylation. Similarly, a ΔG of zero would suggest that the reaction is at equilibrium and has no net change in free energy, which is not the case for phosphorylation during glycolysis. A variable ΔG would imply that the energy change can fluctuate widely based on conditions, but the phosphorylation of glucose under normal physiological conditions has a consistent negative ΔG due to its coupling with ATP.

Thus, the expected change in ΔG when glucose is combined with phosphate is negative, signifying an exergonic reaction that releases free energy and is