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chocoholic_cat
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#1
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Hey was wondering if anyone could help, I just did the beetroot expeiment with changing the temp and observing the transmission percentage and doing the write up now :mad:

Anyways my question is, I need to write explain my observation in terms of the fluid-mosaic model.

Thanks =)

Cat
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leaf
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#2
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At high temperature, the particles vibrate more virgrously and have more collision with the phospholipid membrane(fliud mosaic model) as a result of gaining energy. Since the particle collide with the membrane more frequently, the dye in the beetroot is more likely to diffuse out and the percentage of transmission decrease.

i hope it can help you although some of the concepts may not show clearly.^^
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chocoholic_cat
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(Original post by leaf)
At high temperature, the particles vibrate more virgrously and have more collision with the phospholipid membrane(fliud mosaic model) as a result of gaining energy. Since the particle collide with the membrane more frequently, the dye in the beetroot is more likely to diffuse out and the percentage of transmission decrease.

i hope it can help you although some of the concepts may not show clearly.^^
Thank you sooooooooo much for the help, coz I tried to look it up in the books but had a hard time tying it in with the beetroot experiment =)

Thank you!

Cat
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Ben.S.
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(Original post by leaf)
At high temperature, the particles vibrate more virgrously and have more collision with the phospholipid membrane(fliud mosaic model) as a result of gaining energy. Since the particle collide with the membrane more frequently, the dye in the beetroot is more likely to diffuse out and the percentage of transmission decrease.

i hope it can help you although some of the concepts may not show clearly.^^
Er....isn't it more to do with the lipid strcture (electrosatic attractions and Van der Waals forces) destabilising at higher temperatures? I say this since I don't know if the 'dye' is able to move passively across an intact lipid bilayer without passing through transmembrane proteins (plus, why would beetroot cells have proteins facilitating the passage of dye?). Please correct me if I'm wrong - I'd actually quite like to know.

Ben
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leaf
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(Original post by Ben.S.)
Er....isn't it more to do with the lipid strcture (electrosatic attractions and Van der Waals forces) destabilising at higher temperatures? I say this since I don't know if the 'dye' is able to move passively across an intact lipid bilayer without passing through transmembrane proteins (plus, why would beetroot cells have proteins facilitating the passage of dye?). Please correct me if I'm wrong - I'd actually quite like to know.

Ben
I don't sure about it too......

But, the observation is. as the temperature rises, the decrease of the percentage of transmission.

I would conclude that the diffusion occur mainly as there is a concentration gradient of "dye" or red pigment between the cell and the water. The active transport by the protein also occur, but when the temp. getting higher and higher, the protein would denature and the active transport stop....
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Ben.S.
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(Original post by leaf)
I don't sure about it too......

But, the observation is. as the temperature rises, the decrease of the percentage of transmission.

I would conclude that the diffusion occur mainly as there is a concentration gradient of "dye" or red pigment between the cell and the water. The active transport by the protein also occur, but when the temp. getting higher and higher, the protein would denature and the active transport stop....
Certainly, there is a concentration difference with respect to dye intracellularly and extracellularly - but whether the increase in absorbancy is due to increased rates of diffusion across the bilayer or simply cell lysis (most likely - causing dye to spill into the extracellular solution, as there is no longer anything to contain it), for the reasons that I mentioned before, is debatable. It is extremely unlikely, however, that dye would be actively transported in significant quantities.

Ben
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leaf
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you seems quite reasonable too and i can't sure.........

can anyone help?
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chocoholic_cat
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(Original post by Ben.S.)
Er....isn't it more to do with the lipid strcture (electrosatic attractions and Van der Waals forces) destabilising at higher temperatures? I say this since I don't know if the 'dye' is able to move passively across an intact lipid bilayer without passing through transmembrane proteins (plus, why would beetroot cells have proteins facilitating the passage of dye?). Please correct me if I'm wrong - I'd actually quite like to know.

Ben
But I thought van der waals forces dont disable due to high temp, it is H-bonds which does that, also the highest temp was 80 degrees and although van der waals forces are weak, think its a bit stronger than that?

The dye crossing the lipid bilayer, isn;t the dye quite small and uncharged so wouldn't it just go striaght through?

So would change in transmission % be just due to diffusion?

Or am I being completely stupid and talking crap again...arghhh bio is so hard to understand =(
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Ben.S.
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(Original post by chocoholic_cat)
But I thought van der waals forces dont disable due to high temp, it is H-bonds which does that, also the highest temp was 80 degrees and although van der waals forces are weak, think its a bit stronger than that?

The dye crossing the lipid bilayer, isn;t the dye quite small and uncharged so wouldn't it just go striaght through?

So would change in transmission % be just due to diffusion?

Or am I being completely stupid and talking crap again...arghhh bio is so hard to understand =(
No, you're not talking crap at all. But, in lipid bilayers (it's misleading to call it a 'phospholipid bilayer') Lipids, as you know, are amphipathic (you might not know the word, but you know what it means) molecules - which means they posses a hydrophilic head group and a hydrophobic fatty-acid tail (which sticks into the membrane). In phospholipids (and glycolipids), the upper and lower surface of the membrane is bounded by the hydrophilic (polar or charged) head groups, which are held together in a tightly packed conformation via electrostatic interactions. The tails are generally (further down the molecule - ignoring the buffereing effects of sterols on the upper portion) less compacted and they are uncharged - the only forces keeping them together are VDW forces (the strength of which is inversely proportional to the twelfth power of the distnce, or something like that). As the temperature is raised, the fatty acid tails gain kinetic energy and, hence, move about more - increasing the distances between adjacent tails and, therefore, weakening the effects of the VDW forces. At very high tempeatures (out of the physiological range) both the electrostatic and VDW attractions will not be enough to keep the liquid crystal structure of the membrane intact and, consequently, it may become leaky (pores open) or (at even higher temperatures) fall to bits entirely.

Ben
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Ben.S.
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#10
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Interesting about the dye, though. Is it small and non-polar? I don't know. If so, that would explain linear increases in absorbancy up to a point, at which the absorbancy begins to decrease out of proportion. Is this what was observed, or was it linear all the way?

Ben
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chocoholic_cat
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(Original post by Ben.S.)
Interesting about the dye, though. Is it small and non-polar? I don't know. If so, that would explain linear increases in absorbancy up to a point, at which the absorbancy begins to decrease out of proportion. Is this what was observed, or was it linear all the way?

Ben
Sorry this is a very lazy question, but what;s the difference between a phosolipid and lipid layer?

The results, its not quite linear as in they drop quite rapidly towards the highest tempertaure, but the hydrophilic heads, they have hydrogen bonds so maybe because of the high temp it breaks down, and that's when the dye comes out. Hmm but then again in the lower tempertaures it still come out so maybe it is a bit of both diffision and breaking down of bonds.

The dye.....hmmm lol I have no idea I thought it was uncharged and small because it would certainly explain why it was able to diffise between the lipid bilayer at the lower tempertaures, as dont H-bonds break down round about 40degrees.

Hmm I think I have just well went round in circles saying nothing much o well really do need that brain from santa this yr =)
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Ben.S.
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Phospholipid is a type of lipid. In vivo, membranes are practically never made of phospholipid alone - they also contain sterols (which buffer the effects of temperature on the membrane - very important!) and glycolipids (which tend to make up membranes which curve sharply, due to their 'less bulky' head groups - the 'stacked' thylakoid in plastids, for example). People just say 'phospholipid bilayer' because it makes them sound cleverer - even though it doesn't if you're talking to someone who knows their stuff. As for the results, I would have to say that the initial decrease in %ge transmission was due to the effect of temperature on the rate of dye diffusion across the membrane. After that, though, (at higher temperatures) the lipid bilayer must have begun to 'break', releasing much more dye than possible by diffussion in the same time-frame - producing a much more pronounced drop in transmission at higher temperatures.

Ben
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Ben.S.
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Oh, and phospholipid heads are hydrophilic because they have a base of some sort attached to a phosphate group. They are not always held together by hydrogen bonds - more often than not it is due to ionic bonding or permanent dipole interactions.

Ben
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chocoholic_cat
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Lol my teacher calls them 'phospholipid bilayer' hehe, but then again in his defence he has the droning kinda voice so might have just heard wrongly =)

Btw thank you for all the help, finally got the write up done, lol just hope it makes sense o well will read it through later =)

Thanks again Leaf & Ben =)

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leaf
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#15
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#15
(Original post by chocoholic_cat)
Lol my teacher calls them 'phospholipid bilayer' hehe, but then again in his defence he has the droning kinda voice so might have just heard wrongly =)

Btw thank you for all the help, finally got the write up done, lol just hope it makes sense o well will read it through later =)

Thanks again Leaf & Ben =)

Cat
^^ i think i haven't help much.~~when i come back, i saw a long discussion......

I also thanks you all becasue both of you clear my concept and make me know more~~like a brainstorm~~especially those related to chemistry.

I'm also interested in what are you both studying at.
You both seems quiet good at chemistry but it's really a nightmare of me......>.<
I'm a student in Hong Kong and preparing for the A-level. Nice to meet you all~~

leaf
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chocoholic_cat
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Hey I used to live in hong kong =) but moved here when I was 6, so have to say my chinese is getting quite rusty now. *btw very weird question but was watching the news and they said they ahd a crocodile in HK, did they catch it? lol, crocodile who would have thought =)*

At the moment Im in college *first yr =|* doing bio, chem, hist and maths. Have to say think I made a really bad decision with maths and bio, dont really enjoy it too much but guess the biochem part is quite good and biology do fit quite nicely with chem in some bits =)

chem Im more interested in itthan bio, probs coz chem fits into a tight little box which you can understand but with bio its quite complex

hey leaf, you said you are in HK, wow you are up really late =| isn't it like 1/2 am now?

Cat =)
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Ben.S.
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(Original post by leaf)
^^ i think i haven't help much.~~when i come back, i saw a long discussion......

I also thanks you all becasue both of you clear my concept and make me know more~~like a brainstorm~~especially those related to chemistry.

I'm also interested in what are you both studying at.
You both seems quiet good at chemistry but it's really a nightmare of me......>.<
I'm a student in Hong Kong and preparing for the A-level. Nice to meet you all~~

leaf
Nice to meet you, too. I'm doing NatSci at Cambridge.

Ben
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leaf
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woo..........Great~~

Cat

Yes, there is a crocodile in hong kong and an Australian expert is here to catching it everyday~around a week~......~he'll leave hong kong soon and some chinese expert will come and catch it.

It all from a man who brought it from Mainland and planned to kill it for meal.(as you know, chinese eat almost everything and believe it has some health purpose)

i'm study chin, eng, chem, bio and as phy...i'm interested in bio and like to further my studies in biotechlogy=)......but quite weak in English and chem=(

it's around 2:30am in hk, i haven't sleep because of my chem lab report^^

Ben

woo.....NatSci...

leaf
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chocoholic_cat
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Hmm what's Natsci? *cambs yeaa Im in cambs too, lol, and on a side note wish the stupid rain would stop :mad: but guess we need it for the grass but still *

Crocodile to eat....wow I thought it was just a stupid person keeping it for a pet or something....but eat, now that's as sick as eating snakes etc.

aww reports know the feeling, my hist teacher went mad with hwk this week =(

Anyways nice talking to all of you, have to go now dogs need walk =( *wish it would stop raining*

Cat
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swimming rat
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i only quickly scanned through this post and dont know if anyone corrected themselfs but both of you where wrong in several ways.
The particle collision therory destroying the singer fluid mosaic membrane is well wrong to say the least its also ludicrous. beetroot ceels have no proteins for the diffusion of the betalains that produce the dye. this means they canot pasivley diffuse over the membrane. Using the structure of the singer fluid mosaic membrane is a lot more logical explanation.

The membrane is studed with channel, carrierand glyco proteins. as you are most likely aware proteins denature with increased heat intensity. as the temperature rises the proteins thouroghly denature. as the tertiary structure unfolds they "fall out" of the cell mebrane which is made up of a phospholipid bi layer. as the fall out there are large 'holes' in the membrane the betalaines then mve out of the 'holes' by diffusion (high conc in the cell low conc outside) and the pigment 'leaks' out

sorry if i offended anyone the conclusions you both derived were valid but if you think it through logically could not really have been true
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