Study Notes
Enzymes are proteins that act as biological catalysts, speeding up chemical reactions without being consumed. They work by having a specific active site that fits the substrate, forming an enzyme-substrate complex. Temperature and pH affect enzyme activity by altering the enzyme's shape and function.
- Enzyme — a protein that acts as a biological catalyst. Example: Amylase breaks down starch into maltose.
- Substrate — the molecule upon which an enzyme acts. Example: Starch is the substrate for amylase.
- Product — the substance formed from an enzyme-catalyzed reaction. Example: Maltose is the product when amylase acts on starch.
- Active Site — the region on an enzyme where the substrate binds. Example: The active site of amylase binds to starch.
- Denaturation — the process where an enzyme loses its shape and function due to extreme conditions. Example: High temperatures can denature enzymes.
- Optimum Temperature — the temperature at which an enzyme's activity is at its maximum. Example: Human enzymes typically have an optimum temperature of 37°C.
- Optimum pH — the pH level at which an enzyme's activity is at its maximum. Example: Pepsin works best at a low pH in the stomach.
Exam Tips
Key Definitions to Remember
- Enzyme: A protein that acts as a biological catalyst.
- Substrate: The molecule upon which an enzyme acts.
- Active Site: The region on an enzyme where the substrate binds.
- Denaturation: The loss of an enzyme's shape and function due to extreme conditions.
Common Confusions
- Enzymes are not consumed in reactions; they remain unchanged.
- High temperatures do not always increase enzyme activity; they can lead to denaturation.
Typical Exam Questions
- What happens to enzyme activity at high temperatures? High temperatures can denature enzymes, reducing their activity.
- How does pH affect enzyme activity? Enzymes have an optimum pH; deviations can lead to denaturation.
- What is the role of the active site in enzyme function? The active site binds to the substrate, facilitating the reaction.
What Examiners Usually Test
- Understanding of enzyme specificity and the lock and key model.
- Effects of temperature and pH on enzyme activity.
- Differences between intracellular and extracellular enzymes.