Beetroot cell membranes

Beetroot samples: The same size beetroots will be used throughout the experiment this is to ensure that the impact of the temperature on every sample will stay the same, i.e. if having a bigger beetroot sample less pigments will be released into the test tube at lower temperature, or having a smaller beetroot sample more pigment will be released into the test tube. This error will change the results of the experiment at large. Therefore it is important to insure the sample sizes are the same.

Temperature: As temperature will affect the beetroot cell membrane, I will keep the temperature constant throughout the experiment by using a water bath and measuring the desired temperature using a thermometer.

PH: I will make sure that the pH is stable (constant) and only the temperature varies this is to be done by using buffer in every test tube so as to maintain pH balance for each beetroot sample and insure that pH does not become a variable. PH is important for maintaining the integrity of the cell membrane as integral proteins can denature upon change in pH. Also, presumably the buffer will have the right concentrations of salt or electrolyte’s (ion such as Na, K, Ca, etc.)- that is, the solution and the beetroot cells must be isotonic, so the buffer must be used for each trial-to ensure that the beetroot cell doesn’t lyse due to being placed in hypotonic solution

Additional controls

Time: Amount of time beetroot sample remains in a test tube must remain the same for each trial

Cutting Beetroot: Results could be affected by pigment released due to cutting of beetroot, so wash of initial pigment (excess juice) at the start.

Apparatus

Pipette

Scalpel

Safety goggles

Thermometer

Water Bath

3 250ml beakers

Colorimeter

Tweezers

Stopwatch

Tile

Ruler

19 test tubes (9 in water bath, 9 for when needed for colorimeter and so does not contain specimen, and 1 for resetting the colorimeter).

10ml measuring cylinder

10mm cork borer

Test tube holder

Method

1. Wear gloves and safety goggles, to insure hand are kept clean and that no substances can go into the eye.

2. Cut the beetroot in approximately in half with a knife, so it can be pierced by the cork borer and a cylinder shape specimen can be taken.

3. Pierce the beetroot with a 10mm cork borer, may needed to be pierce at least three times so that there is enough beetroot for the experiment.

4. Using a scalpel cut the pierced beetroot into discs 5mm along it (use ruler to measure), this is to allow it to fit into the test tube and so you have the same size beetroots and so a fair test.

5. Rinse beetroot discs by using distilled water, keep pouring distilled water till the water coming of it becomes colourless rather then red/purple. This is so that no excess ‘juice’ is on each disc after being cut.

6. Clean (rinse) each test tube which is needed, with distilled water to make sure no excess substances are present, so affecting the experiments results.

7. Set the water bath to desired temperature and keep it at a constant, so that when needed the temperature is just right and less time is wasted.

8. Using a measuring cylinder measure 10ml of distilled water, and make sure it’s reading is accurate by looking at the concave/apex at eye level (put measuring cylinder on flat surface). This is so you have the same amount of distilled water in each test tube.

9. In each beaker add 75ml of water and then place them in water bath, so that the water inside them can reach the same temperature as the water bath (and so temperature kept constant).

10. When the temperature of the water in the beaker is the same as the water bath (use thermometer to determine this) add 3 of the test tubes into the beaker and now leave it to equilibrate and the temperature kept constant(temperature of test tube same as beaker, use thermometer).

11. When test tube is at the temperature needed, add discs of beetroot. This is the main aim of the experiment and is to see the affects it has on the water.

12. Using the stopwatch start timing for 10 minutes as soon as the last disc is in the distilled water (make sure that each of the sets of the discs are placed in the test tubes at about the same moment). Timing is needed so that all the beetroots stay in the test tube the same amount of time and so the results are not changed because of the time.

13. After the 10 minutes carefully take out the beaker(with the test tube) out of the water bath and with test tube holder take each test tube out of the beaker and tilt it to about a 45˚ angle(north east) and using tweezers take out each beetroot. This is so that when put in colorimeter the beetroot does not affect the light passing through the test tube (results).

14. Again hold an empty test tube at 45˚ angle and then pour the other test tube (mixture of the water and pigment of beetroot) into it. This is so less time is wasted to wait for the test tube to cool down and so no damage to the colorimeter.

15. Before putting the water mixture test tube into the colorimeter the colorimeter has to be reset to that it is accurate. This is done by getting a test tube and filling approximately ¾ of it with distilled water putting it into the colorimeter and pressing a the button on the colorimeter, this then should set the transmission (%) to 100, meaning that all the light passed through the test tube.

16. Now place each of your test tubes from the experiment into the colorimeter and record the transmission (%). Between each recorded test tube rest the colorimeter as shown above.

17. Add results to results table.

(%Transmission)

Temperature (˚c) Test 1

Test 2 Test 3

Average