Biology Coursework: The Effect of Trypsin on Gelatine.

Implementing: -

1. First, I gathered the necessary equipment:

§ Thermostatically controlled water baths

§ Ice

§ Thermometer

§ Stop watch

§ Test tubes

§ Photographic film (b/w)

§ Syringe

§ Test tube rack

§ Ruler

§ Scissors

§ O.1% trypsin made in pH7 buffer solution

§ Mounted needle

2. I then decided on the range of results and temperatures I was to investigate. I decided to observe 20Ñ", 30Ñ", 40Ñ", 50Ñ", 60Ñ", 70Ñ" and 80Ñ".

3. Next, I label each test tube with the temperature to be investigated and then added 2.5cm3 of Trypsin solution.

4. I ensured that I cut the necessary pieces of film using a ruler and a pair of scissors. I cut pieces that were 2cm in length, and 1.6cm in width each.

5. The only water baths of my choice that were running were at 30Ñ" and 60Ñ". I therefore had to use the Bunsen burner etc. for the rest of the temperatures (excluding 20Ñ"). I kept each test tube heated for 5 minutes.

6. I added the photographic film pieces just before I placed the test tubes in the water baths/ Bunsen burners, and ensured that they submerged fully before I began timing.

7. I carefully and frequently examined each test tube for the time that the film became transparent and listed the result

Results: -

Temperature (Ñ"C) 20 30 40 50 60 70 80

Time taken (minutes) 23:38 16:37 6:06 6:40 7:53 8:24 10:15

Time taken (seconds) 1418 997 366 400 473 504 615

Rate of Reaction -(1/time in mins) 4.d.p 0.0426 0.0606 0.1667 0.1538 0.1250 0.1176 0.0976

It is evident from the graph and the table above, that as the temperature is increased, the amount of light passing through the tested solutions is decreased, and therefore the amount of pigment released from the beetroot samples is increased.

The results produce a graph with negative correlation, a curve that has a negative gradient. The graph shows that as the temperature is increased, the colorimeter reading is decreased. The structure of my results proves my theory correct. The increase in temperature breaks bonds in the (mainly intrinsic) proteins in the cell membranes of the beetroot cells. The tonoplastis a membrane that holds the pigment, when this is affected, the pigment escapes and is released into the cytoplasm. When the outer cell membrane is denatured, the pigment is transferred into the solution. The tonoplastis a membrane that holds the pigment, when this