Multiple Choice
ATP molecules provide energy for cellular activities primarily by which mechanism?
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1. Introduction to Biochemistry
Gibbs Free Energy
Multiple Choice
In the hydrolysis of ATP that releases usable free energy for cellular work, which bond in ATP is cleaved to form ADP and inorganic phosphate (Pi)?
A
The phosphoanhydride bond between the γ (terminal) phosphate and the β phosphate
B
The phosphoester bond between the α phosphate and the ribose 5′ oxygen
C
A peptide bond in an ATP-binding enzyme that is cleaved during catalysis
D
The N-glycosidic bond between adenine and ribose
Verified step by step guidance1
Step 1: Understand the structure of ATP (adenosine triphosphate). ATP consists of an adenine base, a ribose sugar, and three phosphate groups labeled as alpha (α), beta (β), and gamma (γ) phosphates starting from the ribose outward.
Step 2: Identify the types of bonds present in ATP. The key bonds include phosphoanhydride bonds between the phosphate groups (γ-β and β-α) and a phosphoester bond between the α phosphate and the ribose sugar.
Step 3: Recognize that during ATP hydrolysis, the bond that is cleaved to release energy is one of the phosphoanhydride bonds, not the phosphoester bond or any other bond in the molecule.
Step 4: Specifically, the bond broken is the phosphoanhydride bond between the γ (terminal) phosphate and the β phosphate, resulting in the formation of ADP (adenosine diphosphate) and inorganic phosphate (Pi).
Step 5: Conclude that the hydrolysis of this phosphoanhydride bond releases free energy that the cell can harness for various biological processes.
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