Membrane permeability in beetroot cells.

Donald Blankson Hemans

Membrane Permeability in Beetroot cells

Beet root cells contains a red pigment, which is found in the cell vacuole. The vacuole has a membrane in which its function is mainly to prevent the betacyanins from leaving the cell. Leakage of these betacyanins into the external solution can be used as an indication of membrance pereambility changes. As part of my experiment, my aim is to see if temperature affects the membrane by witnessing the amount of betacynanins that leaks from the beetroot cells.

The cell membrane covers the outside of a cell and consists of a double layered sheet of lipid molecules interspered with proteins. It seperates the cell from the external environment, gives phyisical protection and allows the import and export of selected chemicals.

Aim:

I will commence the experiment by placing beetroots in a test tube of deionised water, I will use a range of temperatures in which I will place the beetroot cell to see the damage later on. After placing them in series of test tubes of deionised water for 30 minutes. I will pour out each solution into a cuvette and place it in a colorimeter, This will enable me to witness variations in my experiment.

Prediction:

My prediction to this investigation is that, as the tempertaure of the deionised water increases, so will the membrane permeability of the beetroot cell. In doing so, this will cause the beetroot release more betacyanins, because high temperatures have a tendency to damage cell membrane, thus releasing the red pigment (betacyanin).

If the cell membrane and the cell wall are damaged due to high temperature, there will be nothing to prevent the betacyanin from ecsaping the beetroot cell. Hence Membrane permeability would increase.

Variables :

∙ ...

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Prediction:

Variables :

∙ Time; It is essential that the beetroot cells are placed in the deionised water for the same exact period of time, to ensure this is a fair test.

∙ Tempertaure; Tempertaure plays an important role in this practical. The tempertures have to be kept at chosen temperatures to make sure the results are accurate as possible, and also so that unnecessary damage is not caused to the membrane. I will place thermometers in each temperature bath to make readings a lot easier. Also this will enable me to measure the amount of betacyanin lost in the beetroot cells.

Some of the measuring techniques that I will use during this experiment will be.

∙ A ruler; This equipment will enable me to measure the beetroot cells accurately and to ensure that the beetroot cells are all the same sizes.

∙ Digital stopwatch; This will enable me to ensure the beetroot cells stay in the deionised water for the same exact time.

Measuring cylinder: The amount of deionised water in each test tube has be exactly the same. Otherwise this will create an error in my experiment. Therefore using a measuring cylinder enable my experiment to be fair and accurate.

Apparatus:

Goggles, • Ruler
Lab coat •Colorimeter
Beetroot • Petri dish
Cork borer •Tile
Marker • Spatula
Test tubes
Labels
Test tube holder
Deionised water
Thermometer
Measuring cylinder
Cuvette

Fair Testing:

In this experiment, a fair testing is crucial, as it will indicate whether my results were accurate or inaccurate. I must also ensure all factors are kept the same throughout my practical.

Results:

Membrane Permeability Table

Conclusion, improvements and Evaluation:

My experiment is now complete, and I have witnessed a pattern in my observations. Which is as the temperature decreases, the colorimeter

(% transmission increased).

For example “80°c, percentage on the colorimeter read 64%” and “61°C, Percentage on colorimeter read 75%.”

That is why it is crucial the cell membrane is kept from damage so that Membrane permeablity doesn’t occur.

I can honestly say this proved my prediction and indicates that high temperature does affect cell membrane and causes the cell membrane to malfunction.

Taking a closer look at my graph. I noticed a directly propotional relation between the tempertaure and the percentage transmission.

I also noticed that as the tempertaure increased, so did the red pigment (betacyanin) that left the beetroot cell.

There were major errors in my experiment, For example. The temperatures were not exactly spot on. Hence this gave me a fluctuation in temperatures.

I believe if I were to repeat the experiment three times , I would be able be to obtain more reliable results, simply by getting the average of the results. But at the same time this would increase the chances of uncertainites, as well. Besides that time was not on my side, so repeating the experiment would simply waste time. Since I had to complete the experiment in just over an hour. I believe this was a limitation.

There were also a few things I could take into consideration like the measurements of the beetroot. I cannot honestly say I cut the beetroot to 1 cm approxiamtely because I was in a hurry, since time was against me to complete the practical on time.

Also I cannot determine whether the beetroots were placed in the deionised water for precisely 1 minute. It hereby was an error I made during the experiment.

Also due to the fact I was in a hurry. The beetroot cells did not stay in the test tubes for 30 minutes approxiamately. This could mean the colour may not have had enough time to diffuse out of the beetroot cells. Hence creating an error in my observations.

An error could have also risen from the fact that the beetroots not washed properly . It was also important to have washed out the pigment from the cells that were damaged when using the cork borer.

The anomaly I would say was the sample that was placed in a 5°c bath. Which gave me a relatively large percentage of beetroot pigment concentration, due to the fact that the cell membrane could not work at such a cold tempertaure, hence therefore the pigment (betacyanin) was easily diffused.

On the other hand despite the fact I made a number of errors during the practical and the fact that I did the experiment alone and was under pressure to complete the practical on time. I can truthfully say I did this practical to the best of my ability.

I believe with more practise, I will get the hang of it and next time I would be able to produce a better results.

Teacher Reviews

Here's what a teacher thought of this essay

Stevie Fleming

1st of Jan 1970

** A weak experimental report that lacks the depth required to gain good marks in an A level course. Although some results were obtained the key sections were either missing or lacking in key details. To improve: Research and Rationale There needs to be background research carried out and discussed with respect to the likely effect of temperature on the components of a plasma membrane. The references used to inform the plan should be cited. Planning Although a list of apparatus was present there was no written method and no risk assessment. The key variables need to be listed and the way they will be controlled explained. There was no pilot experiment carried out. Recording There were some results recorded but no replicates were carried out. The table headings were unclear in some cases. Interpreting and Evaluating The interpretation of the results was not linked to biological knowledge and the limitations of the results were not fully discussed. The evaluation was mainly a list of personal failings with regard to measuring and lack of time which would fail to gain credit. The student would need to look more critically at the method ( unfortunately not in the report) and discuss ways that reliability could be improved or the investigation extended.

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