AP Biology / Unit 3: Cellular Energetics
3.3 Cellular Energy
Notes
Cells follow thermodynamics: energy is converted, not created, and some is lost as heat.
- ATP stores energy in phosphate bonds; hydrolysis releases it.
- Energy coupling: exergonic reactions (like ATP hydrolysis) power endergonic ones.
Practice
ATP releases usable energy when:
ATP → ADP + Pᵢ.
An endergonic reaction:
Positive $\Delta G$.
Energy coupling means:
Pairing reactions.
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