Testing the effect temperature has on Beetroot
Introduction:
Beetroot contains a red pigment name betalains, located in the cell vacuole. Normally the pigments cannot pass through the membrane however when the beetroot is cooked, the colour tends to leak. The aim of this experiment is to use beetroot to examine the effect of temperature on cell membranes and link the observation to the structure of membranes. To be able to function properly a cell needs control transport across the partially permeable cell membrane. When there is a rise in temperature of a cell membrane, the structure weakens, until the phospholipids breakdown and carrier proteins denature, which then makes hole in the membrane, causing substances (such as betalains) to leak.
Hypothesis:
My hypothesis is that as the temperature rises, more colour will be lost from the beetroot. This is partly because the rise in temperature will cause an increase in the energy of particles; this means more collision and a faster breakdown of phospholipids, and also because the rise in temperature causes denaturing of carrier proteins, resulting in loss of colour in the beetroot, therefore meaning that a rise in temperature causes substance to leak from cell membranes. This hypothesis is based on my scientific knowledge of membrane structure, and further reading on temperature effects and movement of phospholipids.
Independent variable:
The temperature in which the beetroot was placed
Dependent variable:
The percentage of light absorbed through the different temperatures when the beetroot has been has been left in the boiling tubes for 30 minutes.
Control variables:
The surface area and mass of the beetroot pieces may also affect the amount of the red pigment that leaks out in the time it is measure, as a larger piece would release more pigment, whilst a smaller piece would release less. This means that the pieces must be as similar as possible in size and shape. They will all be as close as possible to 1cm in length and will be extracted using the same cork borer.
Any pigment that is on the surface of the beetroot before it is put into the water will affect the results. To avoid this, the beetroot cylinders should all be rinsed and lightly blotted on tissue. This should be done because the excess pigment will contaminate the water, making the transmission smaller then is should actually be
The volume of water in the boiling tubes will need to be the same as this will affect the amount of light absorbed by the coloured water. If more water were to be place in one of the boiling tubes, the pigment will disperse more, giving the solution a lower transmission than
Method:
You will need a size 4 cork-borer to extract beetroot pieces. A ruler and knife will be needed, also, to cut eight 1cm length slices.
You will need 8 boiling tubes for the different temperature water baths. Label the boiling tubes and fill each with approximately 5cm cubed of distilled water.
Place these in the different temperature water baths (0°c, 10°c, 20°c, 30°c, 40°c, 50°c, 60°c, 70°c) leave for 5 minutes until the water reached the temperature of the water baths. The reason for the use of a water bath is to maintain a steady temperature for a long period of time.
After 5 minutes place the prepared beetroot pieces into the boiling tube.
Leave them for 30 minutes.
After 30 minutes remove the tubes from the water baths and empty the water from those into another boiling tube (do this for all 8). Shake the solution to disperse the dye.
Switch on the colorimeter so it reads % absorbance. A colorimeter will be used as this device can measure the light that passes through a substance, therefore can measure the transparency of the liquid that the beetroot was place in.
Using a pipette measure 2cm cubed of distilled water and place in a curvette. Place the curvette in the colorimeter. Adjust so that it reads 0 absorbance in clear water (do not alter setting again during experiment).