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

The effect of temperature on membrane structure

Extracts from this document...


The effect of temperature on membrane structure. The purpose of my experiment is to use beetroot to investigate the effect of temperature on cell membranes and relate the effects to membrane structure. Background Knowledge The cell membrane is a boundary between the cell and its surroundings. It plays a vital role in regulating materials passing in and out of the cell. The fluid mosaic model of a cell membrane is an asymmetrical mosaic of lipids and proteins, first proposed in 1972. A cell surface membrane has a phospholipid bilayer. This is two layers of lipid molecules held together. The phosphate head of the molecule is polar, meaning the electron sharing between it is not equal and that it is slightly positive or negative. The polar heads attract other polar molecules like water and are hydrophilic (water attracting); the tails of these lipids are non polar and are therefore are hydrophobic (water repelling). The bilayer is formed by the heads facing upwards and the tails facing inwards avoiding any contact with water. The membrane also contains glycolipids (lipid molecules with polysaccharides), glycoproteins (proteins with polysaccharide) proteins and cholesterol. Proteins are found in the inner and outer layer of the membrane. Membrane proteins have hydrophobic areas which occur in the bilayer. Some proteins are fixed, whereas others can move in the fluid phospholipid layer. ...read more.


The following day I will place a beetroot section into each of the boiling tubes each containing 5 cm3 of distilled water and place them in water baths at 0�, 10�, 20�, 40�, 60� and 70�. After leaving the boiling tubes in the water baths for 25 minutes the slice will be removed and the boiling tubes shaken. Afterwards setting up a colorimeter I will set it to % absorbency. I will use a pipette to measure 2cm3 of distilled water into a cuvette and making sure it is placed in with the clear sides correctly I will set it to 0 for clear water. I will then do the same for each dye solution and test the absorbency at each temperature. A colorimeter will measure the percentage of light transmission through a solution. This is compared to a cuvette of distilled water, which is the clearest solution. Variables The independent variable is the factor that affects the dependent variable, any other variable that may affect the dependent variable must be kept constant. The independent variable in my experiment will be the temperature and the dependent variable will be the extent of colour change. I will control the size of the beetroot piece and also keep the amount of water they are in constant (5cm3). ...read more.


An increase in temperature denatured channel proteins. To improve the reliability of my results I would repeat my experiment more times to get a more accurate average. I noticed that the most accurate result I got was for the water bath at 70� which I think is because the water bath at 70� had a lid on it, keeping the temperature constant for the whole 25 minutes. If I was to repeat my experiment I would ensure all the water baths had lids. My points are not all on the line of best fit the most obvious anomaly being 60� , this may be due to experimental errors such as the temperature in the water baths, measuring using beakers and measuring cylinders. When cutting the beetroot there could have been an uneven distribution of dye and I could have cut through membranes causing further inaccuracy and anomalies. Some piece may have also contained more membrane that others. There also may have been a lot of inaccuracy when the boiling tube was placed in ice. This is because the ice is constantly melting meaning it is not always at 0�. If I repeated the experiment I would use a freezer so the temperature remained more constant. Conclusion I conclude that temperature does affect membrane structure. When the membrane is heated its structure begins to fall apart and the cells are denatured, therefore the colour is darker. ?? ?? ?? ?? 1 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Green Plants as Organisms 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 GCSE Green Plants as Organisms essays

  1. Marked by a teacher

    How does temperature affect the permeability of a cell membrane in a beetroot.

    4 star(s)

    Many of the results in this are very close together. Calibration is the process of determining the absolute values. The calibration curve is to see the proportion of pigment that has been released from beetroot. This is used so that we can relate the figures to known standards.

  2. How Temperature Effects the Movement of Pigment Through Cell Membranes

    Beyond this temperature the membrane will start to experience a change in fluidity and stability as the lipids that make up the membrane begin to lose their rigid structure and weaken, eventually leading to perforations along the membrane thus leaking the red pigment anthocyanin by diffusion, as the high concentration

  1. An investigation in to the effect of temperature on the release of pigment from ...

    It also helps to ensure that the cut pieces are cut accurately and precisely. I will also need to set the test tubes containing water to be at the correct temperatures using the water baths for the beetroot pieces to submerge in, hence the tests to be performed.

  2. The factors affecting the rate of permeability in a cell membrane?

    in a colourimeter this was done to see if the colourimeter was working and also to get the reading to the 100% clear mark. * Then a sample of each test tube was taken and was placed in the colourimeter.

  1. An Investigation into the effect of Temperature on the release of Betalain from Beetroot ...

    My control variables will be controlled in the following ways. The size/shape of the beetroot will be controlled by the cork borer and by measuring its length. This has to be done and it is important that it is done accurately because the volume to surface area needs to be the same.

  2. Investigation into the rate at which beetroot dye diffuses through a cell membrane during ...

    if the time varied then I may be investigating the effect of the time rather than the cause of the actual temperature change. Therefore I will keep each beetroot disc in the water bath for exactly 5 minutes. I will use the same beetroot to ensure optimum membrane protein temperatures

  1. Study the effects of temperature on the movement of the red pigment Anthocyanin through ...

    Apparatus: Beetroot sample, cork borer, scalpel, 100cm� beaker, Bunsen burner, heatproof mat, tripod, gauze, test tubes x 9, syringe, thermostatic waterbath, stop clock, colorimeter, cuvettes x 9 Plan: I will firstly cut a beetroot sample using a cork borer, using such as it ensures all the beetroot samples are the same diameter.

  2. To investigate how motion of a dye droplet is affected by the temperature of ...

    12 74 59 30 26 33 14 90 73 35 33 39 16 106 90 40 37 45 18 118 107 46 43 50 20 128 122 51 49 56 22 137 134 57 54 62 24 144 150 66 60 68 26 151 160 70 66 74 28 160

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