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    (Original post by otrivine)
    The amino acids produced are racemic mixture, this is because the (chiral centre) carbon atom is attached to 4 different atoms or groups of atom, and hence, can form 2 isomers which means , 2 non super imposable images of each other, one isomer rotates plane polarised light clockwise while the other isomer rotates plane polarised light anticlockwise, so results in these two isomers/mixture cancelling each other out.

    (Original post by otrivine)
    Hi, can you confirm Zzzyax asked a question about protein hydrolysis , I pretty sure , I am not sure but when a protein is hydrlysed a carbon atom is attached to 4 different variables for optical isomerism to take place and can form mirror images?
    The general formula of an alpha amino acid is RCH(NH2)COOH. If R is H (glycine) then there are two Hydrogens attached to the Carbon so it is not chiral. However in proteins (chain of amino acids joined by amide bonds) you have many different R groups, all of which (apart from glycine as I showed above) have at least one chiral carbon so will exist as a mixture of stereoisomers.

    When you hydrolyze a protein you will pretty much always get a mixture of stereoisomers (unless it is completely made of glycine).

    Whether or not it will be racemic I do not know. Will equal amounts of each left and right isomer of each stereoisomer be produced?
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    (Original post by Mus1995)
    The general formula of an alpha amino acid is RCH(NH2)COOH. If R is H (glycine) then there are two Hydrogens attached to the Carbon so it is not chiral. However in proteins (chain of amino acids joined by amide bonds) you have many different R groups, all of which (apart from glycine as I showed above) have at least one chiral carbon so will exist as a mixture of stereoisomers.

    When you hydrolyze a protein you will pretty much always get a mixture of stereoisomers (unless it is completely made of glycine).

    Whether or not it will be racemic I do not know. Will equal amounts of each left and right isomer of each stereoisomer be produced?
    Thats what I was thinking, if I am not mistaken in an amino acid, the carbon is attached to carboxyl , amine and a variable R group and a single hydrogen atom, alanine has a chiral centre, if it chiral this means there are 4 different groups or atoms attached, so can it not form mirror images?
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    (Original post by otrivine)
    Thats what I was thinking, if I am not mistaken in an amino acid, the carbon is attached to carboxyl , amine and a variable R group and a single hydrogen atom, alanine has a chiral centre, if it chiral this means there are 4 different groups or atoms attached, so can it not form mirror images?
    Use this formula: Number of optical isomers = 2^n where n is the number of chiral carbons.

    If it has ONE chiral centre using the formula above it will have 2 optical isomers.

    I think Zyzaxx was asking would it form a racemic mixture, ie equal amounts of both optical isomers are present. This I am not sure of. :P
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    (Original post by otrivine)
    which one?
    Question 2d which was quoted a link to.. To the other questions I'm sure a racemic mixture would form if there were equal quantities of each optical isomer
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    (Original post by otrivine)
    when the ethanoic anhydride reacts with an alcohol, how does the bond break to form the methyl ehtanoate
    You dont need to know specifically how, however it breaks by gently heating it resulting with two ethanoic acid compounds and one of them reacts with methanol, the other ethanoic acid is just a product. This is why using anhydrides give better yield.
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    does anybody have the answers to the examination style questions from the ocr textbook!?? please and thank youu
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    (Original post by doplop)
    You dont need to know specifically how, however it breaks by gently heating it resulting with two ethanoic acid compounds and one of them reacts with methanol, the other ethanoic acid is just a product. This is why using anhydrides give better yield.
    Got it , thank you
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    (Original post by Anaiza)
    does anybody have the answers to the examination style questions from the ocr textbook!?? please and thank youu
    They come on a disc which comes with the book, I've lost my disc =/
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    (Original post by JP.)
    They come on a disc which comes with the book, I've lost my disc =/
    so have i :/ could somebody send them ?
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    (Original post by Anaiza)
    so have i :/ could somebody send them ?

    (Original post by JP.)
    They come on a disc which comes with the book, I've lost my disc =/
    Here you go. https://mega.co.nz/#!7c8iyJoS!Mqv1fn...rABIf3EiBDS3qM
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    are there any extra questions on the CD? I never got a cd :'(
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    (Original post by master y)
    are there any extra questions on the CD? I never got a cd :'(
    It just has some tips and multiple choice questions; nothing special that will give you an advantage.
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    (Original post by Mus1995)
    It just has some tips and multiple choice questions; nothing special that will give you an advantage.
    thanks
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    Any 1 got any ideas whats going to come up
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    In the June 2010 legacy paper question 4)c) how would you know it????? its chains and ring spectroscopy ?
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    Hi could anyone pweeeaaase explain to me in this Q (jan 12 Q1cii), why in the optical isomers NH2 and H flip?
    I flipped over the NH2 and COOH instead...
    Here is the Q & AName:  ImageUploadedByStudent Room1371324952.700058.jpg
Views: 111
Size:  50.0 KB
    I hope someone can manage to read that and answer my Q. Lol.
    Oh and here is my drawing
    Name:  ImageUploadedByStudent Room1371325005.836093.jpg
Views: 101
Size:  75.7 KB
    THANKS in advanceeee


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    (Original post by l2ob)
    .[/URL][/SIZE]
    that would get you the marks, it doesn't matter which ones are flipped, just an example of one of the possible structures in the mark scheme
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    Thank you!
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    (Original post by master y)
    that would get you the marks, it doesn't matter which ones are flipped, just an example of one of the possible structures in the mark scheme
    Ah okay. you sure? lol. thank you!


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    Can ANYONE please outline how to assemble a high resolution proton NMR or give any advice?! Im dreading seeing a 10 mark question and not getting the right shape! I can analyse it correctly and all, its just putting it together, it always goes wrong D;
 
 
 
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