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asinger96 asinger96
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11 years ago
This should be an easy question for most of you. Say you have the nucleotide sequence on a piece of mRNA:

UUG  CCU   AGU

What amino acid sequence in the protein is produced by this mRNA? My confusion is over whether or not I should make UUG into AAC for example, and call this Aspargine. Do I reverse the codons, or is the amino acid sequence made simply what's given to me above?
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wrote...
11 years ago
you reverse it you are correct.
wrote...
11 years ago
if thats your mrna sequence starting with the 3' end on the left and 5' end on the right, it should be what's given above because translation occurs 5' to 3'. i think you might be confused between transcription and translation.
wrote...
11 years ago
If that's the 5'-to-3' sequence of the mRNA (which is usually how it's written), the anticodon in the tRNA (3'-to-5') would be:

AAC - GGA - UCA

And the amino acid sequence would be:

Leucine-Proline-Serine

Just as a general explanation, DNA is double stranded. In genes, there's the coding strand and the template strand. The coding strand is usually the one that's given when you look up a sequence of a gene, but it's the template strand (the coding strand's reverse complement) that's used as a template to make the mRNA (such that the mRNA is has the same 5' to 3' sequence as the coding strand of DNA). Translation goes from 5' to 3' on the mRNA starting at the START codon (AUG) and proceeding 5' to 3' down the mRNA until a STOP codon is present.  The tRNA anti-codons (which are generally written 3'-to-5') are complementary to the mRNA strand (mRNA with the sequence 5'-ACU-3' will recognize tRNA anti-codons with the sequence 3'-UGA-5'). So, if you're given an mRNA sequence to translate, find the start codon (AUG; codes for Methionine) unless you're told otherwise and look up the given mRNA codon sequence to find the respective amino acid.

There's a useful illustration here:

http://molvis.sdsc.edu/dna/codons.htm
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