• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Investigating the effect of temperature on the permeability of cell surface membranes

Extracts from this document...


Investigating the effect of temperature on the permeability of cell surface membranes Background knowledge of membranes- Membranes are made up of a phospholipid bilayer; a phospholipid is simply a phosphate group (AKA the head) connected to a lipid (AKA the tail). The polar heads are hydrophilic and point outwards to the external environment or inwards to the cytoplasm. The non-polar tails on the other hand are hydrophobic, this means they do not like water; this is why they point inwards. The diagram below shows how a phospholipid bilayer behaves in water (notice the lipid tails are pointing inwards, away from the water). The membrane is not quite as simple as this though, it also has other components to it. There are also proteins in the bilayer which can allow certain molecules in and out of the cell. Small molecules such as the respiratory gases (Oxygen and Carbon dioxide) pass through the membrane by diffusion, in between the phospholipids. Larger molecules however, do not fit in between these gaps. Instead, they pass through channels created by the proteins in the bilayer. This process can be active, which means it requires ATP (active transport) or it can be passive, which means no energy is required (facilitated diffusion). Even though water molecules are very polar, they too can diffuse rapidly through the phospholipids because they are small enough. ...read more.


To get a good set of results, I will be testing at 6 temperatures. The 6 temperatures are 0�C, 20�C, 40�C, 60�C, 80�C and 100�C. I have explained why these temperatures are significant in my predictions. I will repeat the test 5 times for each temperature; I feel this would be enough to get accurate results. If there were any anomalies I could simply disregard them and still have a fairly accurate average. The sample I will cut my samples all from the same beetroot. When I am cutting the beetroot I will cut a 1cm3 sample. These samples will be large enough to produce enough dye but still small enough to easily fit into the test tube. How I would carry out the experiment Once I have all of my samples of beetroot placed into the test tubes of water, I will place them in water baths that will be set at the 5 temperatures I am testing. The samples will be left in the water baths for 30 minutes; this will be enough time for the sample to get to the temperature of water. I must make sure that all of the samples are in the water for a fair result. After the 30 minutes, I will place the samples in a colorimeter. Colorimeters transmit light at the sample and calculate the percentage of the light absorbed. ...read more.


if I did not do this it would have been unfair because different plants may have a higher concentration of Betalain in their vacuoles. The water I put the samples in was distilled water, this was to make sure that the water concentration was 100% at the beginning of the experiment and make sure there were no other chemicals in it. For the first test at 65�C the % transmission read 0%, I consider this result as an anomaly. I believe this because the other 2 results were 22% and 25%, the solution was clearly letting some light pass through as I could see this. This may have been down to human error or an error in the colorimeter which I believe is more probable. As a result of this, I disregarded the anomaly and just done the average of the 2nd and 3rd tests. Doing 3 repetitions of each test may not have given me the most accurate result, I may have got a more accurate result if I done more repetitions (e.g. five). If I had repeated the test more, the anomaly would not have affected the result as much, and my results would have been more accurate. Even with the anomalous result, I still feel my results are accurate enough. The predictions I made before the experiment were correct according to the results, and the scientific background knowledge fits in with the results too. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Marked by a teacher

    Beetroot Experiment. The purpose of this experiment is to determine the effect of temperature ...

    4 star(s)

    At about 20°C proteins start to become denatured loosing their 3-dimensional shape. As the temperature increases above this membrane channel proteins begin to loose shape, preventing the normal movement of substances in and out of the cell. Above 60°C proteins become totally denatured.

  2. Marked by a teacher

    The Effect of Ethanol Concentration on the Permeability of Beetroot Cell Membranes to Betalain

    3 star(s)

    this also proved to be an appropriate amount as it covered the cylinders and was not too much so the pink pigment dispersed too much making visible change difficult to see. Also it was enough to pour into the colorimeter boiling tube.

  1. Marked by a teacher

    Effect of different temperatures on the permeability of beetroot cell membrane.

    3 star(s)

    So the kinetic energy of the diffusion never changed and didn't affect the experiment. So the leakage was at room temp as the beetroot cylinders was only heated for 1 minute, so they cooled back down when the leakage occurred.

  2. Marked by a teacher

    Beetroot Practical Write up

    3 star(s)

    (It may be necessary to stagger the start time for each dilution to give you time to remove the cylinders at the end of the test) Stagger by 30 seconds. 6. Leave the cylinders in the boiling tubes for exactly 30 minutes 7.

  1. Marked by a teacher

    To determine the effect of Detergent on the Permeability of Cell Membranes.

    3 star(s)

    A 10 % detergent solution will be supplied. Beetroot is being used as the pigment is of a very intense colour, so any leakage from the cell will be easily noticeable in the detergent solution. The following apparatus will be needed: * 13 boiling tubes, in which the 10 different concentrations of detergent will be placed, another will

  2. To investigate one of the factors that affects the permeability of cell membranes.

    My graph shows that at 0% alcohol, around 56.7% (3dps) of the light is transmitted through. As you then increase the percentage of alcohol the amount of light transmitted decreases, and the line of best fit starts with a curve.


    ice, we all had to get our own ice using a beaker, and then set it up ourselves. This means that some of us may have some slightly higher temperatures than others, which could be the error that has resulted in these anomalous results.

  2. An experiment to test the effect of different temperatures on the permeability of cell ...

    of the cell membrane is similar to a fluid layer as the phospholipids can move around and change places with each other, and when this happens, sometimes spaces appear between the phospholipids, and the anthocyanin particles could pass through. Although this is possible, but these spaces rarely appear as the movement of phospholipids are limited in normal conditions.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work