Given below are the balanced chemical equation for the hydrolysis of ATP and the

Question

Given below are the balanced chemical equation for the hydrolysis of ATP and the structure of ATP Refer to these to answer the following questions, The standard free energy change for the given reaction is large and negative. Explain the source of free energy in terms of the changes in molecular structure when ATP reacts with water. Consider bond energies, resonance stabilization, and charge destabilization. Is the standard free energy change for the hydrolysis of ATP the same as the actual free energy change that would occur in a cell? Why or why not? Cellular ATP concentrations are maintained well above equilibrium concentrations in cells. Explain how ATP concentration relates to energy changes of reactions that involve ATP and why it is important to keep ATP levels high.

Explanation / Answer

1. Phosphoanhydride bonds that are formed due to splitting out of water in between the two phosphoric acids or in between a phosphoric acid and a carboxylic acid usually contain a huge negative free energy change of hydrolysis. So, in this case, ATP serves as an energy source and the high energy bonds are cleaved by hydrolysis and releases free energy.

2. As the concentrations of ATP, ADP, and Pi may vary in different cell types. Also, the pH value can vary from one cell type to another even it differ from standard pH value inside the cell.So that the actual free energy change also differs from the standard free energy change for ATP hydrolysis.

3. The free energy change depends on the concentration of several cellular reactants that is participated in ATP hydrolysis process. When the cellular particles concentration is higher than the equilibrium value the free energy change i.e.G is greater but in standard concentration the for all the participating reactants the energy change for ATP hydrolysis usually varies in between 28 to -34 kJ/mol. It also depends on the concentration of Mg ion as it helps in stabilization of ATP molecule within the cell.

ATP is an important factor as it stores high energy to drive various cellular function.But ATP is highly unstable molecule so it tends to undergo spontaneous hydrolysis process to produce ADP. For that reason, it is important to keep ATP levels high.

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