Investigate the influence of a variety of treatments on the permeability of the cell membrane.

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Alex Stringfellow

Cell Membranes

Aim

To investigate the influence of a variety of treatments on the permeability of the cell membrane.

        This experiment aims to discover the effect of 6 different treatments on the permeability of the cell membrane.  These will be distilled water, sucrose, sodium hydroxide, hydrochloric acid, ethanol and boiled water.  The treatments include immersion in these solutions, and exposure to high temperature.  The tissue used is from the taproot of a beetroot, and the effect on the membrane’s permeability assessed by the amount of pigment leakage that occurs.

Hypothesis

I predict that the most damage to the membrane will be caused by the acid or the boiling water.  I think that this will happen because generally hydrochloric acid causes more damage to things and also it produces more aggressive reactions causing greater effects this I think means that the acid is more likely to effect or disable the proteins in the lipid bi-layer this means that if this happens the membranes selective permeability will be lessened and the restriction of the flow of pigment out of the beetroot will also be lessened so more pigment can and will flow out.

        I think that the membranes permeability will also be affected greatly by heat, I think that this is because when the molecules are transported over the membrane they are done so with energy so when the water is heated the molecules will gain more kinetic energy so the transport over the membrane will be quick so more pigment will escape.

Planning

In this experiment the thing I will be changing, my independent variable, is the solutions that I am testing to find out the permeability or a cell membrane.  Also my dependent variable, what will be changing because of my change of solutions is the percentage transmissions giving me the results I need to find out what solutions affect a membranes permeability.

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My control variables will be:

  • The size of the beetroot - 1cm x 0.5cm x 0.5cm
  • The amount of each solution used – 10ml
  • The time the beetroot is immersed – 15 minutes
  • 4 pieces of beetroot in each tube

I will be keeping these all the same for each test.  This will help me ensure a fair test.

Equipment

  • Beetroot
  • Large knife
  • Scalpel
  • Forceps
  • 6 test tubes
  • Test tube holder
  • 2 test tube racks
  • 100ml beaker
  • 250ml beaker
  • Thermometer
  • Tiles
  • Chinagraph pencil
  • Bunsen Burner
  • Tripod
  • Gauze
  • Heatproof mat
  • Ruler
  • Colorimeter
  • Curvettes
  • Droppers
  • Stopclock
  • Goggles
  • ...

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