Activation energy

Definition

Activation energy is the minimum amount of energy required to start a chemical reaction. In biological systems, enzymes lower the activation energy needed for metabolic reactions.

5 Must Know Facts For Your Next Test

1. Enzymes lower the activation energy of biochemical reactions, making them proceed faster.
2. Activation energy is usually provided in the form of heat in non-biological systems.
3. In enzyme-catalyzed reactions, the substrate binds to the active site of the enzyme, reducing the activation energy required.
4. The concept of activation energy explains why some reactions are slow or do not occur at all without an enzyme.
5. Catalysts are substances that increase reaction rates by lowering activation energy without being consumed in the process.

Review Questions

• What role do enzymes play in relation to activation energy?
• How does lowering activation energy affect a chemical reaction?
• Why is activation energy important for understanding metabolic reactions?

Related terms

Enzyme:

A protein that acts as a catalyst to speed up biochemical reactions.

Substrate:

The molecule upon which an enzyme acts.

Catalyst: A substance that increases the rate of a chemical reaction without being consumed.