Study Notes
Metabolism encompasses all the chemical reactions within an organism that sustain life, often organized into pathways controlled by enzymes. These pathways can be chains or cycles, allowing precise regulation of biochemical changes through intermediates.
Exam Tips
Key Definitions to Remember
- Metabolic pathways — Chains and cycles of enzyme-catalysed reactions.
- Activation energy — The initial energy needed to start a chemical reaction.
- Competitive inhibition — A molecule similar to the substrate binds to the enzyme's active site, blocking the substrate.
- Noncompetitive inhibition — A molecule binds to an allosteric site, changing the enzyme's shape and preventing substrate binding.
- End-product inhibition — The final product of a reaction pathway inhibits an earlier step, regulating product formation.
Common Confusions
- Confusing competitive and noncompetitive inhibition.
- Misunderstanding the role of activation energy in enzyme reactions.
Typical Exam Questions
- What is a metabolic pathway? A series of enzyme-catalysed reactions organized into chains or cycles.
- How do enzymes affect activation energy? Enzymes lower the activation energy required for reactions.
- What is an example of end-product inhibition? The conversion of threonine to isoleucine, where isoleucine inhibits the pathway.
What Examiners Usually Test
- Understanding of enzyme inhibition types and their effects.
- Ability to explain the regulation of metabolic pathways.
- Knowledge of examples of metabolic pathways, such as glycolysis and the Krebs cycle.