Enzymes (WJEC GCSE Biology): Revision Note

What are Enzymes?

• Enzymes are proteins produced by cells

• Enzymes are biological catalysts

  • Biological = they are produced and function inside living cells

  • Catalyst = they speed up the rate of chemical reactions without being changed or used up

• Enzymes are involved with all the metabolic reactions that occur inside living cells, where they maintain reaction rates at a suitable level

  • E.g. if we did not produce digestive enzymes it would take around 2-3 weeks to digest one meal; with enzymes it takes around 4 hours

• Examples of enzyme-controlled reactions include:

  • Building larger molecules from small molecules

  • Breaking large molecules into smaller molecules

How Different Enzymes are Formed

Higher Tier Only

• Enzymes are proteins, molecules that are composed of many amino acids linked to form a chain, which is then folded into a specific shape

• The specific amino acid sequence of an enzyme is important in determining its structure and therefore its function

The sequence of amino acids determines how a protein folds, and therefore determines its structure and function