Enzyme-controlled reactions

• Give examples of variables that could effect the rate of an enzyme-controlled reaction

  • Enzyme concentration/volume
  • Substrate concentration/volume
  • Temperature of solution
  • PH of solution
  • Inhibitor concentration
• Describe how temperature can be controlled

  • Use a thermostatically controlled water bath
  • Monitor using a thermometer at regular intervals and add hot/cold water if temperature fluctuates
• Describe how PH can be controlled

  • Use a buffer solution
  • Monitor using a PH meter at regular intervals
• Why were the enzymes and substrates solutions left in the water bath for 10 minutes before mixing?

  So solutions could equilibrate/ reach the temperature of the water bath
• Describe a control experiment

  • use denatured enzymes
  • Everything else the same as experiment e.g. same conc/volume of substrate and enzyme, same type/volume of buffer solution, same temperature
• Explain why using a colorimeter to measure colour change is better than comparison to colour standards

  • Not subjective
  • More accurate
• Explain why the rate of reaction decreases over time throughout each experiment

  • Initial rate is highest as substrate concentration not limiting/many E-S complexes form
  • Reaction slows as substrate used up and often stops as no substrate is left