Study Notes
Enzymes are globular proteins that act as biological catalysts, increasing the rate of biochemical reactions by lowering the activation energy threshold. They have specific active sites where substrates bind, forming an enzyme-substrate complex that leads to the conversion of substrates into products.
- Enzyme — A globular protein that increases the rate of a biochemical reaction by lowering the activation energy threshold. Example: Lipase breaks down lipids.
- Active Site — The region on the enzyme where the substrate binds. Example: The active site of lipase binds to lipid molecules.
- Substrate — The reactant in a biochemical reaction. Example: Lipids are substrates for lipase.
- Lock and Key Hypothesis — The idea that the active site and substrate match each other structurally and chemically. Example: Only specific substrates fit into the enzyme's active site.
- Induced Fit Model — Suggests that the enzyme's active site is flexible and reshapes to fit the substrate. Example: Enzymes adjust their shape to bind substrates tightly.
- Denaturation — A structural change in an enzyme that results in the loss of its biological properties. Example: High temperatures can denature enzymes, affecting their function.
Exam Tips
Key Definitions to Remember
- Enzyme: A biological catalyst that speeds up reactions.
- Active Site: The specific region where the substrate binds.
- Substrate: The reactant in an enzyme-catalyzed reaction.
Common Confusions
- Confusing the lock and key model with the induced fit model.
- Assuming enzymes are consumed in reactions.
Typical Exam Questions
- What is an enzyme? An enzyme is a globular protein that acts as a biological catalyst.
- How does temperature affect enzyme activity? Increasing temperature increases activity up to an optimal point, after which activity decreases due to denaturation.
- What happens when an enzyme is denatured? The enzyme loses its shape and function.
What Examiners Usually Test
- Understanding of enzyme-substrate specificity.
- Effects of temperature, pH, and substrate concentration on enzyme activity.
- Differences between the lock and key model and the induced fit model.