BiochemistryLesson 1 of 1 in the course Metabolism

Energy Forms, Gibbs Free Energy, and Activation Barriers

5 flashcards · 5 quiz questions · 5 match pairs · 4 fill-in sentences · English

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Summary

Energy is the ability to do work, and it can take forms that are visible, such as light and motion, as well as forms stored in an object's position or structure. This lesson introduces kinetic, potential, and chemical energy—ideas that help explain how energy moves through living systems.

Kinetic energy is the energy of motion. A moving airplane, a walking person, and rapidly moving molecules all have kinetic energy. Because moving objects can cause changes, they can do work. A wrecking ball swinging into a structure, for example, transfers energy as it collides with the structure.

All flashcards

Gibbs free energy
Energy available to do work after accounting for entropy.
Exergonic reaction
A reaction with ΔG<0\Delta G < 0 that releases free energy overall.
Endergonic reaction
A reaction with ΔG>0\Delta G > 0 that requires free-energy input.
Activation energy
The energy barrier reactants must overcome to reach the transition state.
Catalyst
A substance that speeds a reaction by lowering its activation-energy barrier without changing ΔG\Delta G.

Quiz questions

  1. What does Gibbs free energy describe?Answer: Energy available to do work after accounting for entropy.
  2. For a reaction with ΔG<0\Delta G < 0, which description is correct?Answer: It is exergonic, and its products have less free energy.
  3. What does it mean for a reaction to be thermodynamically spontaneous?Answer: It can proceed without net free-energy input, though it may be slow.
  4. Why do cells exchange matter and energy with their surroundings?Answer: The exchange helps maintain free-energy differences needed for cellular work.
  5. How does a catalyst affect a chemical reaction?Answer: It lowers activation energy without changing the reaction's overall ΔG\Delta G.

Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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