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The Effect of pH on the Plant Cell Membrane

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The Effect of pH on the Plant Cell Membrane

Postby zerobladex » Tue Oct 07, 2008 10:08 pm

How is the cell membrane of a beet cell, affected by acidic and basic levels of pH?

I read that varying levels of pH deteriorate proteins in the cell membrane causing them to leak out red pigment. Is this true for both acids and bases or just one of them? Because I did an experiment where a slice of beet was placed in a 0.01 mol/L solution with nothing happenning, however, when another slice of beet was dropped into a 0.001 mol/L solution, the solution turned pinkish. I'm not sure if this was supposed to happen or if it was an error of some sort.
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Re: The Effect of pH on the Plant Cell Membrane

Postby blcr11 » Wed Oct 08, 2008 1:00 pm

You're going to have to describe your experiment and problem better. The title you gave the thread talks about plant membranes, but the description is all about slices of meat--which is probably what you meant to say in the title, I would guess. The red pigment in red meats comes mostly from a hemoglobin-like molecule called myoglobin. Myoglobin is the intracellular oxygen carrier and doesn't circulate like hemoglobin does with the RBCs. So long as the muscle cell membranes remain intact, you shouldn't see any myoglobin in the solution--indicated by the pink-to-red tinting of the water (presuming, of course, that the meat has been thoroughly rinsed of any residual blood cells--why do you think that might be important for correctly interpreting your results?). If the treatment causes the membranes to lyse, myoglobin is released and the solution turns pink. If you're lucky, the "amount" of coloration is proportional to the "amount" of membrane damage.

OK, so that's the way probably it was supposed to work. I don't know what you treated your meat pieces with. You have two concentrations, but of what? One is acid and one is base? And why the different concentrations? I don't quite understand why you would want to compare 0.01 M acid with 0.001 M base (if that's what you did). If these were NaCl concentrations, both should have been hypoosmotic (at least relative to RBCs in plasama) and both should have resulted in some lysis, but you said this was an experiment about the effects of pH on membrane integrity or something like that. So, you'll have to explain a little better what exactly you did before I can say much more.
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Re: The Effect of pH on the Plant Cell Membrane

Postby canalon » Wed Oct 08, 2008 3:15 pm

blcr11 wrote:You're going to have to describe your experiment and problem better. The title you gave the thread talks about plant membranes, but the description is all about slices of meat--which is probably what you meant to say in the title, I would guess.



Umm our dear VIP, beets are not meat. They might be red but that is probably the only thing they have in common with meat. They grow underground, and they have a weird earthy/sweet taste.

As for the Original poster, it would help if the solution was identified... But keep in mind that some pigments change color with pH (I am not saying that this is what happens here, I have no idea) and that when the beet was sliced many membranes were mechanically damaged, so some leakage of the pigment into the solution should be expected, unless the slices have been carefully washed to prevent that. And then have all the slices been washed equally well?
As for the sensitivity of membranes to pH, I suppose that they are, but I would expect that the change in pH necessary would be quite important. And to make your experiment worthy you should then compare pH rather than concentrations...
And you should take into account osmotic pressure. If your solution is too dilute you might be seeing cells exploding under to high osmotic pressure.

Good luck with your experiments.
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Re: The Effect of pH on the Plant Cell Membrane

Postby blcr11 » Wed Oct 08, 2008 5:24 pm

Sorry. :oops: Could have sworn it said "meat", but clearly it says "beet". My mistake; and all that stuff about myoglobin isn't relevant. But I still don't quite understand what exactly was done--be it beet or meat slices.
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Postby canalon » Thu Oct 09, 2008 2:15 pm

If I read right:
- cut beets in slice
- put slices in solutions of different concentrations (but of what?)
- look at the color of the solution
- discuss the effect of pH on cellular integrity
There is so many holes in the description that I believe the last point is impossible to do unless more details are provided.

And you should not post while waiting for the BBQ to be ready :D
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Postby MichaelXY » Sun Oct 12, 2008 10:33 pm

Beet, Beef, I can see that happening :)
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Postby emmalyy » Mon Dec 08, 2008 2:16 am

I'm guessing you used HCl or NaOH?
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