In this very simple experiment you will simulate the hydrolysis of starch, as caused by the enzyme amylase (which exists in two forms within the body), over a period of time.
The enzyme you will use will be amylase, from a fungal source. This is to replicate the effect of either salivary amylase from saliva, or pancreatic amylase from the pancreas, which would not be so hygienic or convenient!
10cm3 measuring cylinders
plastic dropping pipettes 3cm3
rack for above
recessed plastic tile - for iodine test
warm waterbath - for incubation
hot waterbath - for Benedict's test
It is essential that you do not cross-contaminate plastic pipettes used in this experiment.
Place 1 drop of iodine solution into each of the recesses of a plastic tile.
Using a pipette, add 1 drop of starch solution to the (first) well containing iodine. Note and record the result.
Perform Benedict's test on (a sample of) the starch sol. Note and record the result.
Measure 10 cm3 of starch sol into a boiling tube.
Measure 2 cm3 of amylase solution into another boiling tube.
Place both into the warm waterbath and leave them for 5 minutes to reach the appropriate temperature (equilibration).
Whilst you are waiting, prepare a table for the rest of the results.
Mix the contents of the 2 tubes by pouring, and then replace the full tube in the warm waterbath. Start timing!
Using a dropping pipette, immediately remove some of the mixture and add a single drop to a drop of iodine on the tile. The pipette can be returned to the tube for further samples. Note and record the result.
Rinse the other tube and put it in the washing up bowl!
At regular intervals (every minute):
Remove some of the mixture and add a single drop to a drop of iodine on the tile. The pipette can be returned to the tube for further samples. Note and record the result! Actually you will have a sequential series of samples if you are systematic.
When there appears to be no reaction to this test, proceed to the final stage:
Perform Benedict's test on (a sample of) the reaction mixture. Note and record the result.
Complete your writeup, adding a conclusion.
Can you think of any details you would like to add, or modifications to the procedure?
thermometers to check temperature check enzyme: iodine/Benedict's/biuret repeat with boiled amylase