AS Biology-effect of temperature on diffusion

The rate of diffusion increases with temperature because the molecules are moving more quickly, so everything equilibrates more quickly.
Pigment leaving beetroot is going to be effected by high temperature differently as it will begin to denature proteins and break down cells, releasing the pigment. This is not associated with diffusion.
It really depends on the temperatures you are using - if they are higher than say 60-80 C then this will have effects not to do with diffusion.
If this is a biology practical, then diffusion is not what you're measuring, it's protein denaturing leading to pigment release.

Reply 2

It is still diffusion that causes the pigment to leave the cell though - it's just that diffusion can happen faster when the membrane proteins are denatured as there are then gaps left in the membrane that will lead to faster diffusion out of the cell.

So what I'm trying to say is that you can still talk about diffusion in your theory section.

Reply 3

oxymoron

It is still diffusion that causes the pigment to leave the cell though - it's just that diffusion can happen faster when the membrane proteins are denatured as there are then gaps left in the membrane that will lead to faster diffusion out of the cell.

So what I'm trying to say is that you can still talk about diffusion in your theory section.

But that's not what the graph is going to show - I would have thought the amount of time left is enough to allow equlibration of the surrounding fluid and burst cells (otherwise how do you measure your sample? It doesn't seem to make sense)
The shape of the graph would tell us the truth! Shame he/she isn't online.

Reply 4

twilight

i did that coursework for my as level. Its quite easy, isnt it

Reply 5

OP

thnaks guys for your help - sorry if there was some confusion. i used temperatires ranging from 10-70 degrees (if that chnages anything).
What i wanted was just some theory really to fill out the conclusion as to why the results showed that more pigment was released at higher temps and i heard from someone at school that diffusion was the cause of this. is this incorrect then to think that diffusion is part of the process.

once again thanks for your previous help.

Reply 6

frizzy_locks

thnaks guys for your help - sorry if there was some confusion. i used temperatires ranging from 10-70 degrees (if that chnages anything).
What i wanted was just some theory really to fill out the conclusion as to why the results showed that more pigment was released at higher temps and i heard from someone at school that diffusion was the cause of this. is this incorrect then to think that diffusion is part of the process.

once again thanks for your previous help.

It would be hard to tell how important it is without seeing the graph.

But yes diffusion will play a part in the pigment release. How long did you leave the beetroot in these temperatures?
My guess at what the graph would look like is a small rise from 10-50 degrees then a sharp increase from 40or50 to 70 degrees. Is this right?

Reply 7

OP

Golden Maverick

It would be hard to tell how important it is without seeing the graph.

But yes diffusion will play a part in the pigment release. How long did you leave the beetroot in these temperatures?
My guess at what the graph would look like is a small rise from 10-50 degrees then a sharp increase from 40or50 to 70 degrees. Is this right?

i think i missed out a HUGE step into what i'm investigating - so sorry!!!

the question is: how temperature affects amount of pigment released measured with % transmission of light on a colorimeter.

can't believe i missed this huge detail out.

and my graph decreases so 10 is highest and 70 lowest as the more pigment there is as the temp goes up the less light % that can get through on the colorimeter. hope this all makes more sense now.

Reply 8

frizzy_locks

i think i missed out a HUGE step into what i'm investigating - so sorry!!!

the question is: how temperature affects amount of pigment released measured with % transmission of light on a colorimeter.

can't believe i missed this huge detail out.

and my graph decreases so 10 is highest and 70 lowest as the more pigment there is as the temp goes up the less light % that can get through on the colorimeter. hope this all makes more sense now.

No that's fine, it would just depend on whether you are using transmission/absorbtion.

What shape is the graph?

Reply 9

OP

it's a slow decrease from 10 degrees to 50 and then drops more rapidly to 70.

Reply 10

Golden Maverick

No that's fine, it would just depend on whether you are using transmission/absorbtion.

What shape is the graph?

Yes ... would expect small decrease (probably) at the start followed by a sharp drop at some higher temperature.

As Rob said, the protein denaturing will be the biggest factor, but diffusion rates will also play some part (especially at lower temperatures).

EDIT: good that graph is what I expected ...at the low temperatures it is diffusion controlling the amount of pigment released (through membrane proteins) so the higher the temperature, the faster the diffusion and the more pigment released.
At higher temps when the proteins denature, you get most of the pigment leaking out through the gaps in the membrane, hence the sharp drop.

Reply 11

frizzy_locks

it's a slow decrease from 10 degrees to 50 and then drops more rapidly to 70.

So you can say, as Simon has, that from 10-50 change in diffusion rate is predominant, then denaturation of proteins becomes important as it allows much more pigment to leave the cells.

EDIT: lol. Snap :smile:

Reply 12

OP

ahh brilliant - you guys are the best!! soryy about all the confusion but you guys sorted me out all right. thanks

Reply 13

Golden Maverick

So you can say, as Simon has, that from 10-50 change in diffusion rate is predominant, then denaturation of proteins becomes important as it allows much more pigment to leave the cells.

EDIT: lol. Snap :smile:

We're just obviously the same person :wink:

see you tomorrow at the concert by the way!

Reply 14

frizzy_locks

ahh brilliant - you guys are the best!! soryy about all the confusion but you guys sorted me out all right. thanks

No problem ... best of luck with it :smile:

Reply 15

OP

one more thing actually - do you guys know any more detail that i could add in about the denaturing of the actual cell i.e what actually happens in the cell, to the membrane etc.

Reply 16

The denaturing occurs to the protein.

The heat will disrupt the tertiary structure of the protein by breaking hydrogen bonds and other weak forces hoding the shape of the protein together. Because of this, the protein effectively falls apart and is no longer embedded in the membrane.

Under normal circumstances the dye needs to diffuse out through the protein (as it can not pass through the phopholipid bilayer of the membrane. But, when the protein is denatured, it is no longer embedded in the membrane, so it leaves a gap through which the dye can pass much more freely.

Reply 17

SB