Summary
Enzymes are proteins that act as biological catalysts, speeding up chemical reactions without being consumed. They have specific three-dimensional shapes with active sites where substrates bind. Enzyme Activity involves catabolic reactions that break down molecules and anabolic reactions that build complex molecules. Enzymes lower the activation energy needed for reactions. Factors Affecting Rate of Reaction include temperature, pH, enzyme concentration, and substrate concentration. Investigating Enzyme Activity can involve measuring the rate of product formation, such as oxygen from hydrogen peroxide breakdown by catalase.
- Enzymes — proteins that catalyze metabolic processes Example: Catalase breaks down hydrogen peroxide into water and oxygen.
- Active Site — specific region on an enzyme where substrates bind Example: The lock-and-key model describes how substrates fit into the active site.
- Denaturation — loss of enzyme activity due to changes in temperature or pH Example: High temperatures can denature enzymes, altering their active sites.
- Activation Energy — energy required to start a reaction Example: Enzymes lower the activation energy, making reactions proceed faster.
- Catabolic Reaction — breakdown of complex molecules into simpler ones Example: Cellular respiration is a catabolic process.
- Anabolic Reaction — synthesis of complex molecules from simpler ones Example: Photosynthesis is an anabolic process.
Exam Tips
Key Definitions to Remember
- Enzymes
- Active Site
- Denaturation
- Activation Energy
- Catabolic Reaction
- Anabolic Reaction
Common Confusions
- Confusing the lock-and-key model with the induced-fit hypothesis
- Misunderstanding the effect of temperature on enzyme activity
Typical Exam Questions
- What is the role of enzymes in metabolic processes? Enzymes act as catalysts to speed up reactions without being consumed.
- How does temperature affect enzyme activity? Enzyme activity increases with temperature until it reaches an optimum, after which it decreases due to denaturation.
- What is the difference between catabolic and anabolic reactions? Catabolic reactions break down molecules, while anabolic reactions build them.
What Examiners Usually Test
- Understanding of enzyme structure and function
- Effects of environmental factors on enzyme activity
- Ability to describe and explain enzyme experiments