Membranes

Discussion:

6. The ph solutions that were used were 2,4,7,9 and 10. All of these solutions affected the beetroot, but the most acidic solutions were the ones that did the most damage to the membrane. This is because the ph affects the proteins within the phospho lipid bi-layer. The acidic ph breaks the hydrogen bonds therefore denaturing the proteins and allowing beetroot pigment to secrete form the cell.

7. The ethanol solutions that were used were 11%, 25% and 50% ethanol. The beetroot cell was almost immediately affected by the 50% alcohol but settled as time past. On the other hand the pigment intensity increased through time with the 25% alcohol solution. The ethanol affects the beetroot cell membrane because the ethanol is a very small molecule and rushes in through the phospho lipid bi-layer. By doing this, the structure between the phospho lipid by-layer is damaged not the phospho lipids themselves. This causes the cell to burst and bundles of cell are joined together forming micelles and therefore excreting the pigment of the beetroot into the solution. The higher the concentration, the quicker the cell bursts.

8. The detergent solutions that were used were 1% and 5% detergent. The household detergent is for breaking down grease and fats on surfaces. The detergent does the same for the phospho lipid bi-layer. The bi-layer is made from lipid tails therefore the detergent attacks the lipid and breaks the tails down. By the bi-layer breaking down, this lets the pigment leak into the solution increasing the intensity of the colour of the solution. The higher the concentration of the detergent the more the damage that is made to the phospho lipid bi -layer. This was not what happened in the results. The 1% detergent affected the bi-layer in the long run more than the 5% detergent. This is an unexplained error that occurred due to the accuracy of the experiment.

9. The solutions that affected the beetroot membrane immediately were the most acidic ph (2) solution and the most concentrated alcohol (50%) solution. This is because the solutions were extremely hypertonic to the beetroot cell. Therefore the solutions rushed in and damaged the cell very badly. By damaging the cell, the beetroot pigment leaked into the solution. The other solutions took a longer time to get through the bi-layer because they were less hypotonic to the beetroot cell membrane. But when they did get through, some made more damage to the cell than the more concentrated solution. The ethanol was the quickest to get through the membrane because it is a very small molecule and goes straight through the holes in the bi-layer.

10. The beetroot slices needed to be washed before using them because they could have had other solutions that were on them that could have reacted with the solutions. The beetroot cells were also in the same solution where other beetroots were and were covered in the other beetroot pigment. The beetroot was also washed with distilled water so that the beetroot cell would be turgid so there was a maximum effect with the other solutions.

11. This activity could have been made more quantitive due to many factors. Some of these factors are:

The amount of solution put into each of the Petri dishes could have been measured to make it more accurate

The size of the beetroot cells could have been measured to also be more accurate

The pigment of each Petri dish could have been measured in percentages and the amount of percentage that had increased for the solutions, such as finding the average amount of gain in pigment there was

The cells could have been measured after the 24 hours to see how much it had changed in size and weight to determine if the cell had lost or increased the amount of fluid that was in it

12. The ph, alcohol and detergent affected the cell in different ways. These are due to physical factors of the solutions that were used

Ph.

The ph affected the cell by the proteins within the phospho lipid bi-layer being denatured. The proteins were denatured due to the breakage of the hydrogen bods within the protein and the amino acids.

Alcohol

The ethanol affected the ph by going straight through the phospho lipid bi-layer and attacking the cell itself. The alcohol could rush straight into the cell because ethanol is a small molecule and goes straight through the bi-layer. By doing this, the ethanol bursts the cell and makes it into