Explain how immobilised enzymes differ from free enzymes in their properties and describe two advantages of immobilising enzymes for industrial applications.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Immobilised enzymes are attached to or trapped within an insoluble support or matrix (e.g. alginate beads, a membrane or a solid surface), whereas free enzymes remain dissolved in solution.
Because the active site remains functional, immobilised enzymes retain catalytic activity, but their kinetics can be slightly altered – substrate access may be reduced and the apparent (K_m) can increase.
Industrial advantage 1: the enzyme can be recovered and reused, reducing the cost of the biocatalyst.
Industrial advantage 2: immobilised enzymes are generally more stable to temperature, pH and organic solvents, giving a longer operational life than free enzymes.
Because the active site remains functional, immobilised enzymes retain catalytic activity, but their kinetics can be slightly altered – substrate access may be reduced and the apparent (K_m) can increase.
Industrial advantage 1: the enzyme can be recovered and reused, reducing the cost of the biocatalyst.
Industrial advantage 2: immobilised enzymes are generally more stable to temperature, pH and organic solvents, giving a longer operational life than free enzymes.
Examiner tips
- State the attachment method and contrast with free enzymes; mention kinetic change; give two specific industrial benefits; use terms like ‘recovered’, ‘reused’, ‘stable’
Common mistakes
- Confusing immobilised enzymes with free enzymes; forgetting to mention altered kinetics; giving generic benefits without specifying cost reduction or stability
Mark scheme (4 marks)
- Immobilised enzymes are attached to / trapped within an insoluble support/matrix (e.g. alginate beads, a membrane, or a solid surface), whereas free enzymes are dissolved in solution.
- Immobilised enzymes retain their catalytic activity / active site remains functional, but may show slightly altered kinetics (e.g. reduced accessibility to substrate) compared with free enzymes.
- First industrial advantage: immobilised enzymes can be easily recovered / separated from the product, allowing the enzyme to be reused repeatedly, reducing costs.
- Second industrial advantage: immobilised enzymes are often more stable (e.g. to heat, pH, or organic solvents) / have a longer operational lifespan than free enzymes under industrial conditions.
Key terms in this question
Related
- All IB DP Biology Higher Level (2023 syllabus) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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