Label the appropriate images in the ATP cycle. 1. endergonic 2. ATP 3. more 4. ADP 5. This form of the molecule is stable. 6. ABook 7. phosphate 8. Hence 9. less 10. ATP 11. exergonic 12. reaction 13. action 14. The form of the molecule is stable. 15. Rotel Zoom 16. Prey 17. Next
The Correct Answer and Explanation is:
Correct Labels (Top to Bottom, Left to Right):
- ATP (attached to the top molecule with 3 phosphate groups)
- This form of the molecule is more stable
- endergonic (left arrow pointing to ATP synthesis)
- reaction
- ADP + phosphate (bottom image showing ADP with 2 phosphate groups + 1 Pi)
- This form of the molecule is less stable
- exergonic (right arrow showing ATP hydrolysis releasing energy)
- reaction
Explanation
The ATP (adenosine triphosphate) cycle is fundamental to cellular energy transfer. ATP consists of an adenosine molecule bound to three phosphate groups. It acts as a rechargeable battery for the cell, storing and releasing energy as needed.
In the ATP cycle, ATP is hydrolyzed into ADP (adenosine diphosphate) and an inorganic phosphate (Pi). This reaction releases energy and is classified as an exergonic reaction because it gives off energy that can be used for cellular processes such as muscle contraction, protein synthesis, and active transport. This form of the molecule — ATP — is less stable due to the repulsion between the negatively charged phosphate groups, which makes the terminal phosphate bond easy to break.
Once ATP is hydrolyzed, ADP and Pi can be recombined in a process that requires an input of energy — typically from the breakdown of glucose during cellular respiration. This is an endergonic reaction, as it consumes energy to reform the high-energy phosphate bond in ATP. The result is a more stable molecule in terms of structural conformation (though it stores potential energy due to the high-energy phosphate bond).
Thus, the ATP cycle is a continuous loop of energy capture and release. Exergonic reactions fuel the synthesis of ATP from ADP and Pi, while ATP hydrolysis (exergonic) provides energy to drive endergonic reactions. This cycle ensures cells maintain a ready supply of energy to perform essential biological functions efficiently.
