Final answer:
The correct reaction based on the provided ΔG values for the combining reactions of glycerol with ATP to form glycerol 1-phosphate and ADP is 'Glycerol + ATP → Glycerol 1-phosphate + ADP + H+ ΔG = -21'. This illustrates the coupling of an endergonic reaction with an exergonic reaction, often seen in metabolic pathways like glycolysis.
Step-by-step explanation:
The student is asking which of the given reactions is correct based on the provided ΔG values for two individual reactions involving glycerol, glycerol 1-phosphate, ATP, and ADP. We know that the free energy change (ΔG) for the hydrolysis of glycerol 1-phosphate to glycerol and inorganic phosphate (Pi) is -9, and the ΔG for the hydrolysis of ATP to ADP, Pi, and a proton (H+) is -30. The correct reaction would show the combined ΔG of these two reactions when glycerol is phosphorylated by ATP.
The reaction involving the formation of glycerol 1-phosphate from glycerol and ATP can be derived by reversing Reaction 1 and coupling it with Reaction 2. The ΔG value for this overall reaction can be calculated by adding the opposite of Reaction 1's ΔG to Reaction 2's ΔG. Thus, we reverse the sign for Reaction 1 (from -9 to +9) and add it to the ΔG of Reaction 2 (-30), resulting in a net ΔG of -21.
Therefore, the correct reaction is:
Glycerol + ATP → Glycerol 1-phosphate + ADP + H+ ΔG = -21
This combination of reactions is an example of how cells couple an endergonic reaction (requiring energy) with an exergonic reaction (releasing energy) to drive biological processes. In the context of glycolysis, such coupling is crucial for the generation of energy in the form of ATP. Hydrolysis of ATP plays a key role in providing the energy required for many cellular processes.