What is the amino acid sequence of the polypeptide produced from this sequence?

Met-His-Pro-Ile-Ala-Ser-Phe-Asp




1) First, you have to check orientation. In transcription, the DNA template strand is processed in the 3'->5' direction.  Sometimes you be thrown a curve ball and the orientiation will be wrong, and you'll have to reverse the sequence.  But the sequence given to us runs in the right direction, so we don't have to reverse it.


2) Second, we model transcription by writing the complementary RNA base below each DNA base.  The base pairing rules for going from DNA to RNA are:
C -> G
G -> C
T -> A
A -> U  (there is not T in RNA - it uses U instead)

3'-TACGTAGGCTAACGGAGTAAGCTAACT-5'  (DNA templated strand)
5'-AUGCAUCCGAUUGCCUCAUUCGAUUGA-3' (mRNA)


3) Third, we look for a start codon, AUG.  The start codon indicates the first amino acid for the polypeptide and sets the triplet reading frame.

We are in luck because the first 3 bases are a start codon.


4) Mentally or in writing, break up wht mRNA (starting with the start codon) into groups of 3 bases.  Each one will be a codon.

5'-AUG CAU CCG AUU GCC UCA UUC GAU UGA-3' (mRNA)


5) Use a genetic code table to lookup each codon and write below it the amino acid it codes for.
http://www.lucasbrouwers.nl/blog/wp-content/uploads/2010/04/genetic-code.jpg
5'-AUG CAU CCG AUU GCC UCA UUC GAU UGA-3' (mRNA)
....Met - His - Pro - Ile -- Ala - Ser -- Phe - Asp - [STOP}


So the amino acid sequence is:
Met-His-Pro-Ile-Ala-Ser-Phe-Asp