Energy coupling Original Scenario-Based Practice

Questions

1. 1.

   Astrobiologists studying a subterranean organism isolated from a geothermal crystal cavern discover that it constructs an exotic structural biopolymer via an endergonic condensation pathway with a standard free-energy change of $+18.5\text{ kJ/mol}$. To drive this thermodynamically non-spontaneous synthesis, the cell pairs it with the exergonic hydrolysis of ATP, which releases $-30.5\text{ kJ/mol}$. Which mechanism explains how the cell thermodynamically couples these two processes to achieve the spontaneous synthesis of the biopolymer?

   • A) The cell transfers a phosphate group from ATP to a reactant to form a reactive phosphorylated intermediate, making the overall coupled reaction exergonic.
   • B) The cell utilizes the thermal energy dispersed by ATP hydrolysis to elevate the active site temperature, directly driving the endergonic reaction forward.
   • C) The condensing enzyme permanently decreases the standard free energy of the products below that of the reactants without forming intermediate molecules.
   • D) The cell employs ATP as a stoichiometric allosteric inhibitor to alter the equilibrium constant and prevent the reverse breakdown of the biopolymer.

Answers and step-by-step solutions appear after you finish the test.