Multiple Choice
In the context of Gibbs free energy and cellular metabolism, which molecule is adenosine triphosphate (ATP)?
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1. Introduction to Biochemistry
Gibbs Free Energy
Multiple Choice
In the context of Gibbs free energy, which term best summarizes ATP hydrolysis under standard biochemical conditions (ATP + H2O → ADP + Pi)?
A
Exergonic (negative )
B
Endergonic (positive )
C
At equilibrium (so is always zero regardless of concentrations)
D
Isoergonic (approximately zero )
Verified step by step guidance1
Recall that Gibbs free energy change (\$\(\Delta\[\Delta\) G\$) determines whether a reaction is spontaneous under standard conditions. A negative \$\(\Delta\]\Delta\) G\$ indicates an exergonic (energy-releasing) reaction, while a positive \$\(\Delta\)\(\Delta\) G\$ indicates an endergonic (energy-consuming) reaction.
Understand that ATP hydrolysis (\$\(\text{ATP}\) + \(\text{H}\)_2\(\text{O}\) \(\rightarrow\) \(\text{ADP}\) + \(\text{P}\)_i\$) is a biochemical reaction that releases energy, which cells use to drive many processes.
Recognize that under standard biochemical conditions, the hydrolysis of ATP has a significantly negative \$\(\Delta\)\(\Delta\) G\$, meaning it is exergonic and spontaneous.
Note that the terms 'at equilibrium' and 'isoergonic' imply \$\(\Delta\)\(\Delta\) G = 0\$, which does not apply to ATP hydrolysis under standard conditions because the reaction strongly favors product formation.
Therefore, the best term to summarize ATP hydrolysis under standard biochemical conditions is 'Exergonic (negative \$\(\Delta\)\(\Delta\) G\$)', reflecting the release of free energy.
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