The 3 Simple Rules to Determine the Amino-acid Chain from a DNA Piece Without Errors!

dna_unraveled

RULE ONE:Observe carefully the double stranded DNA given piece. Specify the transcribed strand ( template) and the non-transcribed strand. Write them  on your copybook specifying the name of each. Try to separate every 3 letters by a dash ( because every 3 nucleotides represent one codon and will code for ONE amino acid only).

Transcribed/template DNA strand:

TAC – TGC- CTA- GTC- GGC- GTT- CGC- CTT- AAC – CGC TGT-ATT.

The Non- transcribed DNA Strand:

ATG–ACG–GAT- CAG–CCG–CAA–GCG–GAA–TTG–GCG–ACA-TAA.

RULE TWO: Write the m-RNA in a complementary way to the transcribed DNA strand. (A of the m-RNA  binding with T of the DNA ; U of m-RNA binding with A  of  DNA).

the m-RNA :

AUG–ACG–GAU– CAG–CCG–CAA–GCG–GAA–UUG–GCG–ACA-UAA.

Note: to verify your m-RNA correct sequence, just compare it to the DNA non-transcribed strand, it should have the same sequence but instead of T & m-RNA will have a U.

The non-transcribed DNA strand:

ATG-ACG- GAT– CAG- CCG- CAA- GCG–GAA–TTG–GCG–ACA- TAA.

RULE THREE: Use the genetic code to determine the correct amino-acid sequence in the chain coded by the m-RNA .

amino-acid-table-singlet-code

This genetic code is like a dictionary translating two languages : that of  m-RNA to that of amino-acids. So what you see on your left is the code of the m-RNA ( three letters) and on your right is the symbolic name of the amino-acid. All you have to do is to follow the positions of the letters ( codons of RNA) on the table and find its match of the amino-acid.

AUG–ACG–GAU- CAG–CCG–CAA–GCG–GAA–UUG–GCG–ACA-UAA.

Met – Thr – Asp- Gln –  Pro-   Gln – Ala – Glu – Leu – Ala – Thr – .

Note: Usually the synthesized amino-acid chain starts with Methionine (Met) and the last codon in the m-RNA is a stop codon that does not code to any amino-acids. (The number of amino acids is usually less than the number of the codons of the m-RNA by one )

And here you are, the amino-acid sequence completed!!

Best Regards,

Yusser CHIDIAC Smile

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