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Old 03-05-2013
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DNA Coding and Anti-Coding Sequences

hello!!
i have a mol bio doubt.
hope u can clear it!!!


so for an RNA gene sequence A G C G U A C,
the anti codon mRNA is U C G C A U G.
CORRECT?


for a DNA gene sequence, A G C T G T A C
the anti codon mRNA is a) U C G U C U U G
or b) A G C U A U A C

and the respective tRNA is a) A G C U G U U C
OR b) U C G A U A U G.




which a & b is right???

or have i just confused the concept????
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Old 03-05-2013
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I believe the anticodon is on the tRNA, not mRNA.

The coding strand on the DNA would be the same as the mRNA except the mRNA would have U's instead of T's. Remember the codon sequence is on the coding strand, but we need to use the template DNA strand (read from 3' to 5' end) for transcription to get the same (5' to 3') sequence as the coding strand.

Ex:

For the DNA sequence:

Coding strand -5' ATGCTCGTACTGTAA 3'
Template str - 3' TACGAGCATGACAUU 5'

mRNA would be :

5' AUGCUCGUACUGUAA 3' Notice this is the same as the coding strand, except that U's replace T's.

tRNA (anticodon) would be:

3' UACGAGCAUGAC 5' I wrote this in the 3' to 5' direction for easier understanding, but in the exam they're usually given in the 5' to 3' direction. Also notice that UAA is the codon for 'STOP' and would not have a corresponding tRNA anticodon.

Hope that helps
Please feel free to correct any mistakes I might have made. Cuz I've been done and away with molecular bio for a while now and I may have forgotten something.
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Old 03-05-2013
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my bad. wrong usage of word there by 'anti codon'

ok,i think i got it now. kept messing it up with the A-T-U conversion.


so, for the qn i'd asked, ive now put the 5' and 3' ends..

for a DNA gene sequence, 5 A G C T G T A C 3
template 3 T C G A C A T G 5
mRNA 5 A G C U G U A C 3
t RNA is 5 G U A C A G C U 3


now, its correct, yes?



also,


Quote:
Originally Posted by slowpoke View Post
Ex:

For the DNA sequence:

Coding strand -5' ATGCTCGTACTGTAA 3'
Template str - 3' TACGAGCATGACAUU 5'
Coding strand -5' ATGCTCGTACTGTAA 3'
Template str - 3' TACGAGCATGACAUU 5' <<- UU can't be there in the DNA sequence, right??
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