Summary and Exam Tips for Factors that affect enzyme action
Factors that affect enzyme action is a subtopic of Enzymes, which falls under the subject Biology in the Cambridge International A Levels curriculum. Enzymes are biological catalysts whose activity can be influenced by several factors:
- Temperature: Enzyme activity increases with temperature up to an optimum level (around 40°C for humans), beyond which enzymes denature due to the breakdown of ionic and hydrogen bonds.
- pH: The concentration of ions affects the enzyme's 3D structure by altering the R-groups of amino acids, which can change the active site and affect substrate binding.
- Enzyme Concentration: More enzymes mean more active sites, increasing reaction rates until substrate becomes the limiting factor.
- Substrate Concentration: Reaction rates increase with substrate concentration until all active sites are saturated (Vmax), beyond which no further increase in rate occurs.
- Inhibitors: Competitive inhibitors compete with substrates for the active site, while non-competitive inhibitors bind to an allosteric site, altering the enzyme's shape and function.
- Vmax & Michaelis-Menten Constant (Km): Vmax is the maximum rate of reaction when the enzyme is saturated. Km indicates the substrate concentration at which the reaction rate is half of Vmax; a low Km means high affinity.
- Immobilizing Enzymes: Enzymes can be immobilized in substances like alginate, offering benefits such as reusability, ease of recovery, and increased stability.
Exam Tips
- Understand Key Concepts: Focus on how temperature, pH, and concentrations of enzymes and substrates affect enzyme activity. Remember the significance of Vmax and Km in enzyme kinetics.
- Differentiate Inhibitors: Be clear on the differences between competitive and non-competitive inhibitors and how they affect enzyme activity.
- Visualize Graphs: Practice interpreting graphs related to enzyme activity, especially those showing the effects of inhibitors and substrate concentration.
- Immobilization Benefits: Know the advantages of immobilizing enzymes, such as reusability and stability, which can be crucial in industrial applications.
- Practice Questions: Solve past paper questions to get familiar with the types of questions asked and to reinforce your understanding of enzyme action factors.
