|MadSci Network: Cell Biology|
Dear Rosie, Strong alkais affect membranes by distrupting and removing surface proteins - crucially, though, they leave the phospholipid bilayer intact and so this method can be used to form cell 'ghosts' i.e. protein-less membranes around a cell (e.g. Red Blood cells) so that it can be determined which substances can still enter or leave the cell. These would be crossing the membrane by simople diffusion, since both faciliated diffusion and active transport rely of membrane proteins. Cells treated in this way will also be devoid of virtually all antigens, so can be used in laboratory tissue transplant experiments or to investigate virus infections or hormone receptors. Some cancer treatments work by raising the pH in the target cancer cells and so damaging their membranes and killing them. Strong acids (pH <2.0) denature proteins (both in membranes and elsewhere in the cell) and so are generally lethal. Indeed, acids are widely used in food preservation (picked eggs, onions, chutneys) and also in meat- processing plants to sterilise conveyor belts etc. I hope that helps! Ian
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