Investigating enzymatic reactions

Question 1

Investigate effect of pH on enzyme activity - PRACTICAL 1-3

Answer 1

1) Enzyme catalyses breakdown of starch to maltose. It’s easy to detect starch using iodine solution - present = iodine solution will change from browny orange to blue black.

2) Put a drop of iodine solution using pippete into every well of spotting dish
3) Place Bunsen burner on a heat-proof mat, and a tripod and gauze over the Bunsen burner. Put a beaker of water on top of tripod and heat the water until it is 35 degrees. Try to keep the temperature of the water constant throughout the experiment - use themometer

Question 2

Investigate effect of pH on enzyme activity - PRACTICAL 4-6

Answer 2

4) Use a syringe to add 1cm^3 of amylase solution and 1cm^3 of buffer solution with a pH of 5 to a boiling tube. Using test tube holders, put tube into beaker of water and wait for 5 min

5) Next, use a different syringe to add 5 cm^3 of starch solution to boiling tube.
6) Immediately mix the contents of the boiling tube and start a stop watch

Question 3

Investigate effect of pH on enzyme activity - PRACTICAL 7-9

Answer 3

7) Use continuous sampling to record how long it takes for amylase to break down all the starch. To do this, use a dropping pipette to take a pure sample from boiling tube every 30 seconds and put a drop into a well. When iodine solution remains browny-orange, starch is no longer present.

8) Repeat whole experiment with buffer solutions of different pH values to see how pH affects the time taken for the starch to be broken down.
9) Remember to control any variables each time - make it a fair test

Question 4

Calculate rate of reaction

Answer 4

1000 / time

If experiment measures how much something changes over time, divide amount changed / time