AS/A Biology | Enzymes | Lesson plan

Schedule

Aug 24- Sept13 (3 weeks)

Content

  • Lock and key model
  • Induced fit model : conformation changes
  • Activation energy
  • Enzyme kinetics
  • Enzyme inhibition

Instructional objectives

Students should be able to:

  • explain that enzymes are globular proteins that catalyse metabolic reactions
  • state that enzymes function inside cells (intracellular enzymes) and outside cells (extracellular enzymes)
  • explain the mode of action of enzymes in terms of an active site, enzyme/substrate complex, lowering of activation energy and enzyme specificity * * understand the lock and key hypothesis and the induced fit hypothesis.
  • investigate the progress of an enzyme-catalysed reaction by measuring rates of formation of products (for example, using catalase) or rates of disappearance of substrate (for example, using amylase)
  • investigate and explain the effects of the following factors on the rate of enzyme-catalysed reactions:
    • temperature
    • pH (using buffer solutions)
    • enzyme concentration
    • substrate concentration
    • inhibitor concentration
  • explain that the maximum rate of reaction (Vmax) is used to derive the Michaelis-Menten constant (Km) which is used to compare the affinity of different enzymes for their substrates
  • explain the effects of reversible inhibitors, both competitive and non-competitive, on the rate of enzyme activity
  • investigate and explain the effect of immobilising an enzyme in alginate on its activity as compared with its activity when free in solution

Teaching Process

  • A brief explanation of the induced fit model using the knowledge of structure and mechanism of function of proteins
  • Spreadsheet (MS excel/LibreOffice) simulation of enzyme kinetics
  • Experimental investigation of enzyme kinetics
  • Brief description of Michaelis-Menten model of enzyme kinetics and determining Km
  • Discussing mechanisms of enzyme inhibition

Activities

  • Spreadsheet simulation of enzyme kinetics
  • Investigating the course of an enzyme catalyzed reaction using amylase-starch system
  • Investigating the course of an enzyme catalyzed reaction using Catalase-H2O2 system
  • Investigating effect of temperature, pH, inhibitors and enzyme immobilization on reaction kinetics

Suggested reading / References

Assignments / Evaluation

  • written test
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