Experiments

• Enzyme immobilization


  Mix yeast and sodium alginate together.

  Add calcium chloride solution into a beaker.

  Using a syringe, add drops of yeast and sodium alginate solution into the beaker with calcium chloride.

  Leave this mixture for about 15 minutes to allow the beads to harden.

  Filter the beads out of the solution and rinse them with distilled water.
• What is the enzyme used in enzyme immobilization?

  Sucrase
• Application of immobilized enzymes

  Add sucrose solution to the immobilised enzyme sucrase in a separating funnel and place a beaker underneath.

  Add sucrose solution to the free enzyme sucrase in another separating tunnel and place a beaker underneath.

  Test the solutions in the beaker for glucose using Clinistix.
• Comparison of results from both immobilization experiments

  The solution from the free yeast is cloudy because the free yeast is not separated from its product.

  The solution from the immobilised yeast is clear because the free yeast is separated from its product.

  Therefore, the advantage of using immobilised enzymes is that the product can be easily separated from the enzyme and the enzymes can be reused.
• Components for test on effect of temperature on Catalase Activity

  Enzyme: Catalase

  Source of enzyme: Celery

  Substrate: Hydrogen peroxide

  Product: Oxygen and water
• Test for effect of temperature on catalase activity


  Chop celery and place it in a graduated cylinder.

  Add one drop of washing-up liquid and pH buffer 9 into the graduated cylinder.

  Add Hydrogen Peroxide (H2O2) into a test tube.

  Place the graduated cylinder and test tube into an ice-cold water bath for a few minutes.

  Add the Hydrogen Peroxide to the graduated cylinder and mix it carefully.

  Immediately begin a stopwatch for one minute.

  Note the volume of foam that has been produced in one minute.

  Repeat this procedure using water baths at 20C, 40C, and 60C.
• Results of temperature catalase activity test

  The most amount of foam is produced at 20oC, so the rate of enzyme activity is greatest at this temperature.

  At 60C and 0C, no foam is produced, as the enzyme and substrate molecules are moving too slowly to react.

  20c is optimum temperature for enzyme activity
• Other components of temperature catalase activity test

  Washing up liquid - used to create foam

  pH buffer - kept constant, acts as control

  Water bath and thermometer - keeps graudated cylinder at specific temperature and monitors it
• Test the effect of pH on Catalase activity 


  Place chopped celery, one drop of washing-up liquid and pH buffer 4 into a graduated cylinder.

  Place hydrogen peroxide in a test tube.

  Place the test tube and the graduated cylinder into a water bath of 25C for a few minutes.

  Add the hydrogen peroxide into the graduated cylinder and swirl the cylinder carefully.

  Start a stopwatch for one minute.

  Measure the amount of foam produced in this time frame.

  Repeat this experiment with a pH buffer of 7, 9, and 13.

  Draw a graph of the results showing the volume of foam produced against the pH.
• Results of test of effect of pH on catalase activity


  The greatest volume of foam was produced at pH 9.

  Little or no foam was produced at pH 4 and pH 13.

  pH 9 is optimum
• Isolating DNA from plant tissue

  Peel kiwi and chop into small pieces

  Place kiwi into mixture of 3g salt, 10cm3 washing-up liquid and 100cm3 of water

  Place beaker into 60c water bath for 15 minutes

  Place into cool ice water for 5 minutes

  Add to blender for 3 seconds

  Filter mixture using coffee paper

  Add protease

  Add freezer-cold ethanol

  Lift DNA strands by twisting glass rod in the ethanol
• Why use coffee paper for filtering DNA?

  Has slightly larer pores than filtration paper to allow DNA to pass through
• Why freezer-cold ethanol?


  Room temperature ethanol denatures DNA
• What does protease do?


  Break down the protein histone
• Why 3 seconds in the blender?

  Just long enough to break down the cell walls but not long enough to destroy DNA strands
• Result of isolating DNA

  The extracted DNA appears as a white, stringy mucus.
• Apparatus for experiment investing light activity on photosynthesis

  Lamp

  Elodea - aquatic plant so bubbles of oxygen are seen more easily

  Thermometer

  Water bath - stays at 25c

  Sodium Hydrogen Carbonate - keeps concentration of carbon dioxide constant
• Results of test on influence of light activity on photosynthesis

  When the light intensity increases, the number of oxygen bubbles increases. This means that the rate of photosynthesis increases.

  This is only up to a certain point. After which, as the light intensity continues to increase, the rate of photosynthesis levels off the Elodea is then said to be light-saturated.

  Some other factor is now controlling the rate of photosynthesis and this is referred to as a limiting factor.