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Food Test – Enzymes

AIM                                                                                    

Perform an experiment to determine the sensitivity of enzymes to temperature changes.

HOW DOES IT WORK?

Time allocation: 45 Min

Enzymes are biologically important chemicals produced to breakdown macro-particles such as proteins into smaller molecules in a process known as metabolism. The enzymes latch on to a molecule (in this case a protein) and with the help of a catalyst, in a process called the Lock and key process, the protein is broken down into various molecules that are used by the body to build important tissues.

The Biological enzyme washing powder demonstrates this in this experiment. This technique is used by forensic anthropologists, paleontologists and other scientists to clean biological compounds off bone samples. In the experiment the reduction in staining of the cloth is reliant on the presence of the biological enzyme washing powder. The boiling water degraded the enzymes in the washing powder, meaning that the enzymes will not be as effective.

YOU SHOULD KNOW THE FOLLOWING ABOUT ENZYMES…                                                   

  • Enzymes are proteins
  • Enzymes are specific in their reactions
  • Enzymes are sensitive to temperature changes
  • Enzymes are sensitive to pH changes
  • Enzymes are biological catalysts – that lower the energy necessary for metabolic processes.

APPARATUS

  • 3 x 400ml glass beakers
  • 3 x petri dishes
  • Thermometer
  • Measuring cylinder
  • Forceps
  • Glass rod (Stirring Rod)
  • Spoon end Spatula
  • Boiling water
  • Markers – to mark the different beakers
  • Biological washing powder ( Must have red and blue particles)
  • 3 pieces of white cotton cloth – 5cm x 5 cm
  • Tap water
  • Eosin Y Stain
  • Bromothymol Blue stain
  • Food colouring stain

METHOD:

  1. The 3 pieces of cloth cut each cloth into 4 pieces, there should be 12 pieces in total.
  2. Keep 3 of the pieces unstained and clean.
  3. Take 3 new pieces of cloth and stain them equally with one of the types of stain.
  4. Do this for the remaining 6 pieces of cloth, staining 3 each with the second and third stain.
  5. Mark the three beakers and three petri dishes as A, B and C.
  6. Put 10 ml (2 teaspoons) of washing powder in each beaker A and B.
  7. Boil the water in the kettle – add 75 ml of boiling water to the washing powder in beaker A
  8. Add 75 ml (use measuring cylinder) of Cold ice water to B
  9. And add some tap water to C.
  10. Remember beaker C will only contain tap water and NO washing powder.
  11. Use the glass rod and stir beaker B, make sure that all the washing powder is properly dissolved in the water.
  12. Stir beaker A until all the washing powder is dissolved.
  13. Use the thermometer – to make sure that the temperature in beaker A remains at between 800 and 950 C.
  14. Put a piece of stained cloth of each of the 3 stains and the clean piece of cloth in beaker A, B and C.
  15. Make sure that the cloth and water are properly mixed.
  16. Leave the stained cloth in the glass beakers for about 15 minutes.
  17. Remove the pieces of cloth very carefully with the tweezers, rinse for 2 seconds without rubbing it.
  18. Put each of the pieces of cloth on a petri dish, which is marked in the same way as the beakers – A, B and C.
  19. Observe the three pieces of cloth.

OBSERVATION:

Fill in your observations in the following table for each stain:

CONCLUSION:

The reduction in staining of the cloth is reliant on the presence of the biological enzyme washing powder. The boiling water degraded the enzymes in the washing powder, meaning that the enzymes where not as effective.

PRECAUTIONS:

  • Do not rub the cloth during the rinsing process.
  • Stains must be the same on all three pieces of cloth.
  • Make sure to follow instructions precisely to ensure accurate results.
  • Workstations must always be kept need and tidy.