Effect of Ethanol on Beetroot Membrane

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Biology Coursework

Hypothesis: To investigate the effect of different concentrations of ethanol on the permeability of beetroot cell membranes.

Prediction: By exposing a membrane to a solvent, ethanol, it will increase its permeability. So the higher the concentration of the solvent, the more permeable the membrane will be. But if the concentration of the ethanol is beyond a certain limit, it may break down the cell membrane to the point where there is in fact no overall effect as the ethanol would disturb the lipids in the membrane.

Therefore, more of the red pigment in the beetroot would leak as the lipids control the substances that enter and leave the cell membrane.

However the ethanol might also impair particular proteins or denature the structure as protein has a tertiary structure. Higher concentrations of ethanol would destroy hydrogen bonds that clasp the protein structure. As the lipids and proteins in the cell membrane would be destroyed, the pigment is able to leak from the cell at a higher rate due to there being no cell membrane holding it in the cell.

Diffusion to the cell membrane

Cells must acquire needed ions and molecules from their surrounded extracellular fluid meaning that they must be transported through the cell membrane. This happens by diffusion, which is movement of substances from a high concentration to a lower one through a partially permeable membrane. As ethanol would also be surrounding the cell in a high concentration, it would also be diffused therefore destroying the permeability of the cell membrane. Diffusion is also used to transport other ions and molecules such as oxygen and carbon dioxide. Water also diffuses through the membrane, which is called osmosis.

Diffusion and Facilitated Diffusion (Passive transport):
Another type of diffusion also happens in the cell, facilitated diffusion. Hydrophilic molecules which are small and polar, like oxygen can pass easily through cell membranes by normal...
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