How Enzymes Speed Up Reactions?

The effect of an enzyme on activation energy. Without affecting the free-energy change (∆G) for a reaction, an enzyme speeds the reaction by reducing its activation energy (EA). Source: Urry, Lisa A.. Campbell Biology (p. 155). Pearson Education. Kindle Edition. Campbell Biology Proteins, DNA, and other complex cellular molecules are rich in free energy and … Continue reading How Enzymes Speed Up Reactions?

The Activation Energy Barrier

Energy profile of an exergonic reaction. The “molecules” are hypothetical, with A, B, C, and D representing portions of the molecules. Thermodynamically, this is an exergonic reaction, with a negative ∆G, and the reaction occurs spontaneously. However, the activation energy (EA) provides a barrier that determines the rate of the reaction. Source: Urry, Lisa A.. … Continue reading The Activation Energy Barrier

Equilibrium and Metabolism

Equilibrium and work in an isolated hydroelectric system. Water flowing downhill turns a turbine that drives a generator providing electricity to a light bulb, but only until the system reaches equilibrium. Source: Urry, Lisa A.. Campbell Biology (p. 149). Pearson Education. Kindle Edition. Campbell Biology Reactions in an isolated system eventually reach equilibrium and can … Continue reading Equilibrium and Metabolism

Free Energy, Stability, and Equilibrium

The relationship of free energy to stability, work capacity, and spontaneous change. Unstable systems (top) are rich in free energy, G. They have a tendency to change spontaneously to a more stable state (bottom), and it is possible to harness this “downhill” change to perform work. Source: Urry, Lisa A.. Campbell Biology (p. 148). Pearson … Continue reading Free Energy, Stability, and Equilibrium