TTTA
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Can someone tell me the Affect of temperature on Cell membrane please, ?
Thanks you
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Wat:Shark:Where
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I think the diffusion rate across it increases
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TTTA
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Why is that?
sorry have to hand in an essay tomorrow and can't seem to find anything about this.
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Wat:Shark:Where
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I'm going to be honest

and say I don't have a clue

our teacher mentioned it in passing. I suppose it could have something to do with the heat giving more energy to all the particles which in turn increases the number of collesions which makes everything go faster
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TTTA
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Oh thanks that actually makes sense. Also i was just told by a friend that it also affects the structure of the cell membrane. low temperature =solid high temperature= liquid.
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Wat:Shark:Where
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ah k cool, I think i'm covering that this week so its nice to go in a little prepared.
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LiamSwainy
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The proteins in the cell membrane denature at a certain temperature (it's hight in plants), leaving gaps, so things such as pigment diffuse out of the cell easier.
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Kestrel_Lover_Sophie
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Hmm... I sort of got the impression that as the temperature increased the phospholipid molecules moved round more and so left gaps between them where large substances could pass through. This is why cholesterol is more abundant in the cell membranes of organisms aadapted to hot climates - because it provides stability to the membrane and so stops this happening.
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nadroj
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yea the bonds between the phospholipids will weaken as molecules vibrate with increased kinetic energy, i think the implications of this will be above your current level so id jus say this could cause gaps allowing substances to pass through.

the biggie is really just effect of temperature on proteins - channel and carrier. altering the structure which could allow for bigger or non-specific molecules to pass through or prevent complimentary proteins and substrates binding which means certain molecules which would normally be carried into the cell may not be.
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Medicine Man
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(Original post by Kestrel_Lover_Sophie)
Hmm... I sort of got the impression that as the temperature increased the phospholipid molecules moved round more and so left gaps between them where large substances could pass through. This is why cholesterol is more abundant in the cell membranes of organisms aadapted to hot climates - because it provides stability to the membrane and so stops this happening.

thats correct :yep:
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7589200
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hmm under very high temperature...you can get protein denaturation. Lets say the ion channels denature. Ionic gradients are disappated (augmented by cell membrane destruction - for reasons described above) and the cell loses control over its volume homestatsis. This can lead to the cell entering a downward necrotic spiral which could end with cell death. Also, yes, it speeds up diffusion across the membrane.
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anhbui
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Thankyou, i found all these comments very useful so much better than my teacher's explaination
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olafcutex
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just read your textbook- it is there to read
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Shadoo
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(Original post by olafcutex)
just read your textbook- it is there to read
This thread is over 5 years old.
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olafcutex
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yeah, but some people still have these
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adsgiuagbdabso
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(Original post by TTTA)
Can someone tell me the Affect of temperature on Cell membrane please, ?
Thanks you
Well, the cell membrane consists of a phosphilipid bilayer which allows certain chemicals through and keeps other harmful chemicals out. The cell/plasma membrane also consists of:

Intrinsic proteins (which allow certain chemicals through like glucose in facilitated diffusion).

Extrinsic proteins (Which are used for cell reception).

Glycolipids and Glycoproteins (Collectively called Glycocalyx, they are used for cell identification and in some cases such as your gut wall, for protection).

Cholesterol (which insures that the cell membrane is not too fluid or too permeable).

If you noticed, the molecules mentioned here are made up of:

- Proteins

- Lipids

and are also selectively permeable.

With temperature increase this means:
Proteins in the membrane change shape, and can eventually denature if the temperature is too hot - a bit like the albumen in your egg turning white in a frying pan. This means a few molecules can no longer can pass though other (mostly harmful) chemicals can pass though as intrinsic proteins change their shape.

Lipids in the membrane, like cooking oil in the a pan, becomes more fluid when temperature increases. The membrane can become too fluid and essentially, break apart if the membrane reaches too high a temperature.

A bit like water and a teabag, when you increase temperature, diffusion occurs faster and molecules that are insoluble become soluble: which is not always a good thing as harmful substances can pass through the membrane more easily.

With temperature decrease this means:
Lipids, olive olive oil in a fridge, becomes more viscous. If it becomes too cold this will cause the phosphilpids in the membrane to become too stiff, preventing growth and movement.

If you try putting cold water on a teabag, not much happens. The same is with the phosphilipid membrane. This can cause some problems: important molecules such as oxygen and glucose, and hormones such as steroids do not diffuse through the cell properly and carbon dioxide out of the cell does not diffuse out of the cell properly.

In extreme cases cytoplasm can freeze and pierce the membrane - the cause of why freezing your red pepper turns it to mush.

Hopefully this helps: It really helps to remember stuff using examples in everyday life.
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