cell membranes?

Søren Laurentius Nielsen nielsen at virgil.ruc.dk
Fri Oct 19 02:46:55 EST 2001


I would say that it is more a question of heat affecting the membrane
lipids rather than the proteins. The membrane is largely composed by
phospholipids, and with higher temperature the membrane becomes more
fluid (in pretty much the same way ordinary fat melt on a hot pan) and
loses its integrity: It becomes more leaky. The opposite happens in
the cold: The membranes becomes more stiff. To work properly - and for
the transport proteins to work properly - the membranes needs to have
a certain viscosity, not too stiff and not too fluid. Organisms
adapted to different temperatures among other things have memebranes
designed to work at relevant temperatures.

On Thu, 18 Oct 2001 20:19:39 +0100, "Peter R Clayton"
<claytons.claytons at btinternet.com> wrote:

>Could you help me with some biology problems that I am having?  If you could
>provide some help in the area of cell membranes or know of any good sites
>realting to my problem, it would be much appreciated...
>
>  In beetroot cells, the red anthocyanin pigment occurs in the vacuoles.
>Each vacuole is surrounded by a tonoplast membrane and outside it, the
>cytoplasm is surrounded by the plasma membrane.
>
>  I conducted an experiment where I took a core of beetroot and placed in
>into distilled water of differing temperatures (45-80 degrees celcius).  I
>found out that more pigment comes out of the beetroot if there is a higher
>temperature.
>
>  I believe this is due to the membranes (tonoplast AND outer plasma
>membrane) being affected somehow?
>  I think that on a microscopic level, at higher temperatures, the protien
>structures (e.g. carrier protiens?) are being either sped up by the increase
>of temperature or completely being denatured on the cell membranes.  This
>could possibly allow the diffusion of more anothocyanin?
>
>  There is also the role of the collision theory which would mean molecules
>are moving much faster and can escape through the membranes faster?
>
>  Are there any more suggestions or explanations for this effect of
>temperature on the movement of pigment through the cell membrane?
>  Very much appreciated,
>Peter Clayton
>
>

Søren Laurentius Nielsen
Department of Life Sciences and Chemistry
Roskilde University, Denmark
nielsen at virgil.ruc.dk
http://virgil.ruc.dk/~nielsen




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