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Protein synthesized (Chem) Question HELP

  1. Dec 9, 2006 #1
    I am having trouble answering the following question any help would be greatly apperciated.

    1. A protein must be synthesized by a cell. Part of the amino acid sequence in this protein is:


    -Ala-Gly-Thr-Leu-

    The codons for these amino acids are:
    Gly -- G G C
    Leu -- C U A
    Thr -- U A U
    Ala -- G C A

    Write the base sequence for the complete chain as given and the complimentary bases as would be found in the DNA from which it was taken.

    I am completely confused on how to appoarch this problem...

    It said the whole sequence however only part is given. So what I am assumping it is G C A G G C U A U C U A? But as far as complimentary bases I am at a lost. Any help would be great. Thanks.
     
  2. jcsd
  3. Dec 10, 2006 #2
    After trying it a bit more on my own I got this.

    G - C
    C - G
    A - T
    G - C
    G - C
    C - G
    U - A
    A - T
    U - A
    C - G
    U - A
    A - T

    (On the left side is the bcomplete chain and on the right is the complimentary bases)

    Can anyone verfiy this please? Thanks!
     
    Last edited: Dec 10, 2006
  4. Dec 10, 2006 #3

    iansmith

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    The complimentary sequence is ok but your complete sequence (the one on the left) is incorrect.

    Do you know the difference between RNA and DNA in terms of base pair composition?

    The answer to this question should help you find and correct the mistakes.
     
  5. Dec 10, 2006 #4
    I am a bit confused. I thought that when it comes to paring that you just pair T's with the A's and A's with the U's. And of course- C's with G's and G's with C's. I am greatly confused :( there are roughly 10 problems similar to the question above that are due tomorrow. I was hoping to use this question as a template for my other questions. Can you or anyone please be more specific as to what is wrong? Thanks!
     
  6. Dec 10, 2006 #5

    iansmith

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    When you are talking about DNA, the base pair are A, T, G and C

    When you talking about RNA, the base pair are A, U (instead of T), G and C.

    You pairing is fine but you have to make sure that you are using the right base pair. If the question asks about DNA, you sequence should have T's and not have U's. If the question asks about RNA, then your sequence should U's instead of the T's.

    Codon's for amino acid are encoded by transfer RNA so the sequence will have U. Therefore when the question ask about the DNA sequence, you cannot use the codon sequence as is, you must change U's for T's.

    You may want to look at the following pages for some background info:
    http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Nucleotides.html
    http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Translation.html
     
  7. Dec 10, 2006 #6
    oh. I understand now, thank you for the links and the clarification. Time to get busy on the other problems.
     
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