Summary
Enzymes are biological catalysts that speed up chemical reactions in the body without being consumed. They are proteins with specific active sites that bind to substrates to form enzyme-substrate complexes, facilitating reactions. Enzymes function optimally at specific temperatures and pH levels, and their activity can be affected by factors such as temperature, pH, enzyme concentration, and substrate concentration.
- Enzyme — a protein that acts as a biological catalyst to speed up chemical reactions. Example: Catalase breaks down hydrogen peroxide into water and oxygen.
- Active Site — the region on an enzyme where the substrate binds. Example: The active site of amylase binds to starch molecules.
- Denaturation — a process where the enzyme loses its shape and function due to extreme temperature or pH. Example: Boiling liver tissue denatures catalase, stopping its activity.
- Optimum Temperature — the temperature at which an enzyme's activity is highest. Example: Human enzymes often have an optimum temperature around 37°C.
- Lock and Key Hypothesis — a model explaining enzyme specificity where the substrate fits into the enzyme's active site like a key in a lock. Example: Only specific substrates can bind to the active site of an enzyme like amylase.
Exam Tips
Key Definitions to Remember
- Enzyme: A protein that acts as a biological catalyst.
- Active Site: The region on an enzyme where the substrate binds.
- Denaturation: Loss of enzyme structure and function due to extreme conditions.
Common Confusions
- Confusing enzyme activity with enzyme concentration.
- Misunderstanding the effect of temperature and pH on enzyme activity.
Typical Exam Questions
- What is the role of enzymes in metabolism? Enzymes speed up metabolic reactions by lowering activation energy.
- How does temperature affect enzyme activity? Enzyme activity increases with temperature up to an optimum point, then decreases.
- What happens to an enzyme when it is denatured? It loses its shape and cannot bind to substrates.
What Examiners Usually Test
- Understanding of enzyme specificity and the lock and key hypothesis.
- Effects of temperature and pH on enzyme activity.
- Ability to explain enzyme action using examples like catalase and amylase.