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    I got it at last!!!
    Copper sulphate is a salt with no electronegative charge but as soon as it is put in with the carboxil groups of the protein it disassociates into CU2+ inons(like in the benadiks test) and attaches 2 the slightly negative hydrogen at the peptide bonds pulling them apart.

    if u dont understand feel welcom 2 e-mail me on
    [email protected],com

    can i just say "piss off" to all the people who say that they r some anuses from uni who can solve our coursework problems with some *******s about sach 3, and then include a link to a porn site. message: U R LOSERS

    Originally posted by Unregistered
    Counts for 16 marks in the OCR version :O

    16, which is then scaled down to 8

    Originally posted by Unregistered
    That's not quite how it happens in this case.
    What actually happens is heavy metal ions (ie copper in your case) are highly electropositive. they combine with COO- groups and disrupt ionic bonds. thus denaturing the protein.

    Hope that helps i'm doing it

    Amino acids form the structure of egg albumen, within the protein of the egg albumen there are ionic bonds between the –COO groups on one amino acid and the NH2 groups on the others.
    Amino acids are able to form a variety of chemical bonds with other reactive groups so as copper is a heavy metal and is highly electropositive (has positively charged particles) when copper ions are added (when we mix the copper (II) sulphate with the egg albumen) they are more electro statically attractive, therefore they bond in favour of the weaker existing ionic bonds, this causes the shape of the protein to be altered and thus the protein is denatured.

    very funny

    your website realy helped me with my biology coursework

    does anybody know how to use a colorimeter?

    people - i am trying to do my preliminary and prediction section of my planning and have no idea what to put! any ideas?

    Nice 'n' simple way of doing it, guys - no colorimeter or fancy stuff needed. Instead, use the wonderful trial-and-improvement technique we learnt in Year 9 Maths and the following fact - egg albumen is more dense than water. Denatured egg albumen has almost the same density as water. So, what you do is this: make your various solutions, stick in 1ml of egg albumen, put your thumb over the end and shake it a little. Then leave it in a test tube rack for five minutes - any unreacted albumen will sink to the bottom of the test tube.

    Someone else in my school came up with the following: Egg albumen goes through filter paper. So does water. So, you add 1 ml of albumen to 10 ml of varying concentrations of CuSO4, pass the resulting mixture through filter paper (after shaking), dry out the filter paper and then weigh it. The only problem here is that you won't always get exactly the same amount of egg albumen, even if you do use a 1ml burette (which don't exist, as far as I know), and the filter paper will weigh a different amount every time.

    Also, can I point out that CuSO4 contains nothing but Cu(2+) and SO4(2-) ions. No Sash-3, unless it's unrefined and obtained through dodgy industrial methods.
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    Does anyone have any results of their pre-lim that they would be willing to share with me for a secondary source?. in exchange I can provide a number of v.usefull links regarding the background information including interactions and modifications of salt bridges. D.S bonds, and believe it or not interactions of R groups. I could provide info on re-coiling theory which explains the 'opaqueness'. All this information and more just for the results of your preliminary experiment, thats a great deal. believe this ammounts to over a weeks research and in the process I have gurru'd myself in the arts of protein interactions.

    E-mail [email protected]: [email protected]

    Originally posted by Unregistered
    Egg Albumen is a globular protein held together in the usual manner by interaction between R groups.

    Some of the bonds between R groups are Ionic, ie a positively charged R group is attracted to a negatively charged R group and the force of attraction holds the shape of the protein.

    CuSo4 disociates into Ions in solution. These Ions are also attracted to the charged R groups. the positive Cu ions are attracted to negative R groups, the Sulphate ions to the positive R groups. They effectively neutralise the charge on the R groups so that the R groups no longer bind to each other. This allows the protein to uncoil into long strands.

    Some of the bonds in the portein strand are polar, slightly charged at one end.

    H groups are slightly positive, and become attracted to the slightly negative O end of OH groups. As the protein has uncoiled the H and OH groups are free to line up. The resulting hydrogen bonds cause the molecules to stick together. It is this more compact regular arrangement of molecules that blocks the light and turns the albumen white.

    Hope that's of some help. Mine has to be in tommorrow.
    --------------------------------------------------------------------------------
    I was wondering for my introduction do i have to talk about the stuff above. Like what it is and how?
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    this is wrong. the copper ions bind to the carboxylate ions which can br present in both R groups and the c-terminus of the poly peptide. the recoiling may present a situation where certain hydrophobic groups are exposed to water. in abid to keep these groups away from water a number of proteins, maybe even thousands, may organise themselves as to put their hydrophobic groups together. this clumping of proteins is what the opaquness IS!

    Originally posted by aysha
    any enzymes involved?
    does it need to be timed for fair test?
    how ph change scintif kwnol?
    it is **** all 2 do with emzymes

    and stop cheating by commin on here
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    i KNOW it **** all 2 do wi enzymes. recoiling occurs in all globular proteins (not just enzymes). and exchanging links isnt cheating!

    What sort of things are you guys revising or expecting for the exam itself??

    Because that is worth a whole lot more marks than this little piece.

    i know there is a part on microscope work but do we have to write up lots of essays in the exam???


    Alex
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    The work in the practical exam will broadly fit into three categories. Enzymes, microscope and food tests. It will be in two of the three. So revise on microscope (especially how to calculate magnification, actual size, appeaent size- they love asking you this one) , food tests and enzymes which includes work on proteins. As for the proper exam im revisin everything!!!

    has anyone actually done the practical exam?
    I'm doing it tommorrow and my teachers aren't helping.
    What should i revise and is it hard.

    ps please dont post the actual questions- thats cheating.

    The bacto 7 in the copper sulphate actives the polymorphide bonds in the egg albumen. Dont worry polymorphide is just a more inteligent way to say ionic bonds. The denaturation of the egg albumen causes an increase in heat and a slight increase in pressure. This means the polymorphide bonds to bond with the peptide bonds and the bacto 7 bonds to the remaining free R-group. The 3D structure mutates and this causes denaturation.

    I asked my teacher and he said this answer would get you full marks for the scientific knowledge section.

    Hopes this helps!

    E. Baldwin

    is every one on OCR doing their practical exam 2moro (13 may) for AS?
 
 
 

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