Jul 7, 2009
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Alright.... I have another question... again from achiever test 2

If three identical anticodons of GAU are found matching consecutively along an mRNA frame, what will be the corresponding base sequence on the original DNA stretch?



A. CUACUACUA
B. CTACTACTA
C. CUTCUTCUT
D. GAUGAUGAU
E. GATGATGAT


Correct Answer: E

Anticodons complementary to codons along the mRNA are direct representation of base sequences found along the DNA stretch where transcription has earlier taken place, except for the fact that each uracil (U) in tRNA should respectively be replaced by thymine (T). This should easily lead to the final answer of GATGATGAT.

why isn't the correct answer B? Am I misunderstanding this question altogether or just need a good review of this topic? :confused:
 

yumi43

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look at it this way:

DNA (5' to 3')

mRNA (3' to 5')

tRNA (5' to 3')

if you line it up like so, u have your original DNA strand, then mRNA is transcribed, and the anticodon (which is on tRNA) is paired up with the codon on mRNA. so tRNA reads exactly the same as DNA, except for U/T. does this make sense? sorry, i'm not as eloquent with my explanations as some other people on this site...
 
Jul 26, 2009
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B would be the sequence for the mRNA...the mRNA sequence came from the DNA strand so the original DNA would be complementary to the mRNA and the anti codon would be complementary to the mRNA
 

razblo

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Nov 30, 2008
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You have to, for a lack of a better term, translate the sequence from anticodon (tRNA) --> codon (mRNA) --> DNA

So it would look something like this: GAU (tRNA) --> CUA (mRNA) --> GAT (DNA)

The key to the problem is that it says an anticodon (tRNA) which is complementary to a codon, mRNA, which is complementary to DNA.


I believe the reasoning I gave is accurate. Either way it worked itself out to the right answer :p
 

dentrilla

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Aug 15, 2008
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B would be the sequence for the mRNA...the mRNA sequence came from the DNA strand so the original DNA would be complementary to the mRNA and the anti codon would be complementary to the mRNA
Answer B has T's in it, therefor its not the mRNA

You have to, for a lack of a better term, translate the sequence from anticodon (tRNA) --> codon (mRNA) --> DNA

So it would look something like this: GAU (tRNA) --> CUA (mRNA) --> GAT (DNA)

The key to the problem is that it says an anticodon (tRNA) which is complementary to a codon, mRNA, which is complementary to DNA.


I believe the reasoning I gave is accurate. Either way it worked itself out to the right answer :p
correct:thumbup:
 
Sep 19, 2009
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look at it this way:

DNA (5' to 3')

mRNA (3' to 5')

tRNA (5' to 3')

if you line it up like so, u have your original DNA strand, then mRNA is transcribed, and the anticodon (which is on tRNA) is paired up with the codon on mRNA. so tRNA reads exactly the same as DNA, except for U/T. does this make sense? sorry, i'm not as eloquent with my explanations as some other people on this site...
?????