Membranes Under Stress

Membranes Under Stress

Properties of Cell Membranes

Aim:

Investigate the effect of different substances on beetroot cell membranes. From the results, make some references about the structure of cell membranes.

Materials:

Refer to sheet.

Method:

Refer to sheet

Results:

Table 1: Intensity of pigment colour in solutions

Time (from start) Distilled Water pH

2 4 7 9 10 Alcohol

1% 25% 50% Detergent

1% 5%

Observation 1 1 3 2 1 0 0 1 2 3 2 1

Observation 2 1 4 3 0 1 1 1 3 4 4 1

Observation 3 2 3 4 1 2 1 1 2 3 5 2

Discussion:

1. Does pH have an effect on beetroot cell membranes? Was time a factor? Explain your observations.

According to the results (above), the lower the pH the higher the effect on the beetroot cell membranes; there was a very low colour change in the surrounding medium when a pH level was greater than 7. This may have occurred because pH 7 is neutral and a pH greater than 7 is basic or alkaline. At a pH level greater than or equal to 7, the solution was unable to breakdown the beetroot cell membrane because it is a strong base, which does not have the properties to breakdown a cell membrane. The solutions with a pH level of less than 7 had a higher amount of red pigment in the surrounding medium. This is because a pH of less than 7 is acidic and therefore has a greater effect on the beetroot cell membrane. The acidic pH solution broke down the beetroot cell membrane, and therefore the red pigment leaked into the surrounding medium.

From observations (above), it does not seem that time was a significant factor, in considering the effects of pH in the experiment. Throughout the whole experiment, there was not a big difference in pigment colour in the solutions, the results were constant.

2. Does alcohol (ethanol) have an effect on beetroot cell membranes? Was time and/or concentration a factor? Explain your observations.

From the results (above) it is considered that the higher the concentration in the alcoholic solution, the more anthocyanin will escape into the surrounding medium. The alcoholic solution with a concentration of 1% alcohol had a constant effect of slight leakage of red pigment. The cell membrane was slightly damaged; there was an equal concentration of alcohol inside and outside of the cell. The solution with a concentration of 25% had a .The solution with a concentration of 50% broke down the cell membrane. Alcohol is able to dissolve into the semi-permeable membrane and pass through into the cell, due to this process the cell membrane is broken down; the alcohol enters the cell quicker then other substances. Therefore, even a small amount of alcohol can damage the cell membrane, releasing anthocyanin into the surrounding medium.

3. Does detergent have an effect on beetroot cell membranes?

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