MadSci Network: Cell Biology

Re: pH and the cell membrane

Date: Tue Jun 7 10:40:35 2005
Posted By: Ian WHITE, Secondary School Teacher, Biology 11-19, Godalming College
Area of science: Cell Biology
ID: 1108774713.Cb

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!

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