A Study On The Effects Of pH, Temperature and Solvent On Cell Membrane

Beets, botanically known as Beta Vulgaris. The leaves have been eaten before, but the beetroot was generally used medicinally before 1800’s. Scientific background for beetroot is that the pigments cannot go through membranes but they leak out when the beetroot is getting heated or when beetroot is put in alcohol Beetroot is a vegetable which is used in food making and it contains red pigments called betalains, which are located in the cell vacuole.

We conducted this experiment so that we can find out when a person heat a beetroot what happens to its colour at different temperatures. The membrane must be disrupted if a scientist wishes to extract the pigment. The purpose of this investigation was to study the effects of environmental changes on the permeability of living beet root cells.

Materials and Methods-

Everyone was divided into groups of 6 and each group member was assigned a letter from A to F. Everyone picked a letter from A to F in the group and did what they were suppose to do.

Person A had to cut out the beet slices approximately 2mm thick into 80 equal pieces and then place the beet pieces in a 400 ml beaker and rinse them thoroughly in cool running tap water, then Person A had to collect the “beet juice” in 2 test tubes halfway and then give it to the pH group. Person A had to rinse the beet pieces until the water runs clear and distribute the beet pieces to other group members, when done help out person C and D. Person B had to clean the test tubes and collect test tube racks and other general material like paper towel to clean up, ice cubes to use it for procedure C and then help out other people in the group.

Person C and D had to set up Procedure A: Effect of PH on the Cell Membrane and collect the red “beet juice” from the rinsed beets and see how it reacts with acid (Beet juice + few drops of 0. 1 mol/L acid) and base (Beet juice + few drops of 0. 1 mol. L base), and then write down the observations. Then they had to label 7 test tubes from letters A to G with the stock solutions that they were given 0. 1 mol/L HCL and 0. 1 mol/L NaOH. They used graduated 10 mL pipettes to prepare the test tubes from A to G and put 10 mL of 0. 1 mol/L HCL into test tube labeled as A.

Then Person C and D pour 10 mL of 0. 01 mol/L HCL into test tube B (1mL HCL from tube A + 9 mL water), then put 10 mL of 0. 001 mol/L HCL into test tube C (1mL HCL from tube B+ 9 mL water). Then they pour 9 mL of tap water into test tube D and 10 mL of 0. 1 mol/L NaOH in test tube E. In test tube F they pour 10 mL of 0. 01 mol/L NaOH (1 mL NaOH from tube E + 9 mL water) and 10 mL of 0. 001 mol/L NaOH (1 mL NaOH from tube F + 9 mL water) into test tube G. They removed 1 mL from test tubes C and G to leave 9 mL in each tube so that all the test tubes have the same amount.

Person E had to set up Procedure B: The Effect of an Organic Solvent on the Cell Membrane and lable 2 test tubes with the letter H and I and filled with H- 9 mL of methanol and I- 9 mL of acetone. Person F had to set up Procedure C: Effect of temperature on the Cell Membrane and labeled 6 test tubes witht the letters J through O and set them up as J- heated to 100 degree C (boiling water), K- 70 degree C, L- 50 degree C, M- 35 degree C, N- 10 degree C, and O- 0 degree C (freezing).

Then person F immersed 5 beet pieces into the boiling water at the same time for exactly 1 minute and after 1 minute he transferred them to test tube K. After letting the water cool to 70 degree C person F repeated the same step as before by adding the cold water, and then transferring the 5 beet roots to test tube K after 1 minute. Then person F repeated the step (1) for test tube L (50 degree C) and M(35 degree C). After getting the cold water from the ice beaker at the front of the lab person F add 5 beet pieces in the cold water 10 degree C for exactly 1 minute and then immediately transferred them to test tube N.

At last person F obtained 5 frozen beat pieces and added them to test tube O. At the end all the 6 members of the group added 5 beet pieces to each test tube at the same and took observations at 5 minutes, 15 minutes and 15 minutes.

Results-

We found out through our observations that the 2mm thin slices had a larger surface area and leak more pigment therefore the beetroot first bursts the cell membrane and kills the cells.

The effects of heat on the beetroot were; at very high temperature the liquid becomes more fluid and the colour becomes darker and darker after every 10 minutes we observed. Cell membrane contains of 70% of the protein and when we heat the protein it gives more energy to it. So basically we learned that beetroot changes colour when heated at very high temperature (100 degree C).

Discussions

The colour of the solution becomes darker as the temperature increases. As the temperature increases the water becomes more fluid and cell membrane denatures.

Cell membrane disrupts when beetroot is heated, freezing the beetroot causes ice crystals to rupture the cell membrane and at the lower temperature there is less leakage of pigment compared to high temperature. The colour of the solution becomes darker as the pH increases and its cloudy pink when pH decreases. The beet root cell membrane denatures membrane proteins at extreme high pH, but at lower pH the protein denatures more which means there are holes in the cell membrane. Solution with the highest pH has very low concentration of hydrogen ion or none.