Required practical 1 - enzymes Flashcards
(Catalase practical) Why should the potato paste be smooth?
Lumps would affect surface area and rate of enzyme controlled reaction
(Catalase practical) Why did the disc rise?
Oxygen formed from the breakdown of hydrogen peroxide forms on the surface of the disc, becomes less dense so rises
(Catalase practical) How would you calculate rate from an end point reaction?
1 / time taken in secs
Why should smaller intervals be used?
To obtain more accurate optimum
Why complete repeats?
A more reliable mean and allow identification of anomalies
Why is a buffer solution not used?
If change in pH is an indicator of rate of enzyme controlled reaction
Why would a colour standard be used?
If rate is calculated by time of indicator to change colour)
Why are test tubes left in a water bath for 10 minutes before enzyme added to substrate?
to equilibrate / reach the temperature of the water bath
Suggest improvements
Use a buffer solution to prevent changes in pH
Use a thermostatically controlled water bath
What is a standard control for any enzyme reaction?
Boil the enzyme
proves that the enzyme has an effect (it is still there but denatured)
Explain how the active site of an enzyme causes a high rate of reaction
- Lowers activation energy
- Induced fit causes active site to change shape
- ES complexes cause bond to break
Use knowledge of kinetic energy to explain why a lower temperature would affect the result
- molecules have less kinetic energy so move more slowly
- decreased rate of diffusion
- fewer ES complexes formed
