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Beetroot Plasma Membrane Investigation

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Beetroot Plasma Membrane Investigation

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Beetroot Practical 2.8

An investigation to find out whether the raise of temperature will increase the permeability of the cell membrane: The question being answered from doing this experiment is ‘How do different temperatures affect the permeability of the plasma membrane of beetroot?’ Beetroot contains red pigments called betalains, located within the cell vacuole. Normally the pigments cannot pass through membranes but they leak out when the beetroot is cooked or placed in alcohol. The aim of this practical is to use beetroot to examine the effect of temperature on cell membranes and relate the effects observed to membrane structure. To function correctly a cell needs to be able to control transport across the partially permeable membrane.

I believe that with the increase of temperature applied onto the plasma membrane, the structure of the membrane will become damaged and the intrinsic and extrinsic proteins in it will eventually denature causing the pigment within the vacuole of the beetroot to leak out.

Method

List of equipment and apparatus used in this experiment:
➢ Colorimeter
➢ Thermometers
➢ Water baths at various temperatures
➢ Stopclock
➢ Test tubes
➢ Small measuring cylinders
➢ Cuvettes
➢ Cork borer
➢ Mounted needles
➢ Beaker about 250 cm³
➢ Blue Filter

The dependent variable was the absorbance.
We measured it by using a colorimeter which compares the amount of light getting through a solution with the amount which can get through a sample of pure solvent. It was controlled by filling the test tubes with distilled water.

The independent variable was the temperature of the water. We controlled it by using a water bath which contains a thermostat that regulates the temperature and keeps it constant.

Instructions:
1. Use a cork borer to cut some beetroot tissue into discs about 3 mm thick. 2. Place...