ATP Transitional Reasoning Download PDF

Questions

1. 1.

   A researcher studies an endergonic metabolic reaction in which a cell converts substrate X into product Y. In cellular systems, this reaction proceeds efficiently when coupled to ATP hydrolysis through an enzyme that creates a phosphorylated intermediate. However, when the researcher adds an isolated ATPase that hydrolyzes ATP into ADP and inorganic phosphate in the same vessel without forming this intermediate, no product Y is synthesized. Which deduction best explains why uncoupled ATP hydrolysis fails to drive the synthesis of product Y?

   • A) ATP hydrolysis in free solution absorbs thermal energy from the medium, rendering the local environment thermodynamically unfavorable for substrate X.
   • B) Uncoupled ATP hydrolysis dissipates the released free energy as heat instead of transferring a phosphate group to form a more reactive intermediate.
   • C) The inorganic phosphate ions released into the solution act as irreversible inhibitors that alter the chemical identity of substrate X.
   • D) The conversion of substrate X into product Y requires the simultaneous cleavage of all three phosphate groups rather than terminal phosphate hydrolysis.