Investigating the Effects of Temperature on Cell Membranes

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Investigating the effects of temperature on cell membranes
Independent variable: Temperature of beetroot
Dependent variable: Absorbency of light
As temperature rises to its optimum temperature, the absorbency of light will increase because protein is an enzyme and will therefore be affected by temperature. This is because more beetroot dye will pass through the cell membrane and then into the distilled water. The deeper the colour of the beetroot dye, the higher the absorbency of light. Beetroot vacuoles have red pigments which can’t pass through the cell membrane there will therefore be an increase in the amount of red pigment diffusing out of the cell. This is because there is a high concentration of red pigment in the cell and no concentration in the water. Increasing the temperature will also provide kinetic energy to the phospholipid bilayer, increasing the movement of the individual phospholipids – this will cause gaps to appear allowing the dye to pass through. Membrane proteins may be denatured by the higher temperatures and their tertiary structure will unravel also allowing dye molecules through the membrane. Apparatus:

* Access to several water baths set at a range of temperatures, or beakers containing water at different temperatures (note 3) * Thermometers, 1 for each water bath
* Kettle, to provide boiling water for the water baths
* Ice bath (a beaker of water surrounded by ice)
* Scalpel, 1, or sharp vegetable knife
* Tile, 1
* Forceps or mounted needles to ‘handle’ beetroot cores * Ruler, up to 15 cm, 1
* Distilled water, in wash bottle
* Measuring cylinder, 10 cm3, 1
* Test tubes, 1 for each temperature of water bath
* Paper towels
* Marker pen
Temperature / °C| Absorbency / A|
| 1| 2| Mean|
0| 0.24| 0.28| 0.26|
Room temp (22)| 0.39| 0.41| 0.4|
40| 1.22| 1.31| 1.25|
60| 2.00| 2.00| 2.00|
1. Collect 3 or 4 beetroot cores from...
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