Matthew L. answered • 03/12/25
BA in Biochemistry with 7 Years of Teaching Experience
This question has two steps:
Step 1: Convert the DNA to mRNA.
You need to know what base pairs (letters) match up when DNA is converted to mRNA. A becomes U. C becomes G. T becomes A. G becomes C.
Using the sequence provided as an example:
DNA: 3’ATTGCGAGTCATTAC...
mRNA: 3'UAACGCUCAGUAAUG...
Step 2: Use a Codon Chart to convert mRNA to the polypeptide chain
If your teacher did not provide a Codon Chart you can find one by Googling Codon Chart, it is a good idea to print one out for reference. Both the circular and square format will work, use whichever you find easiest to wor with.
Codons are sets of three bases (letters). Find your set of three letters on the chart and the chart will tell you which amino acid it corresponds to. Below I have split the mRNA sequence into sets of three so it is easier to see the codons. The lines are just a tool for us they do not have any meaning and are not necessary for a complete answer.
mRNA: 3'UAA|CGC|UCA|GUA|AUG...
UAA = Stop Codon, A stop codon signals the end of protein synthesis for the cell.
CGC = Arginine which can be represented by the three-letter abbreviation Arg or more simply R. I will just list the three-letter abbreviation going forward
UCA = Ser
GUA = Val
AUG = Met
Full Example:
DNA: 3’ATTGCGAGTCATTAC...
mRNA: 3'UAACGCUCAGUAAUG...
Polypeptide: StopArgSerValMet...
In your question, it states that introns are underlined and exons are not underlined. Introns do not code for anything and should be removed from the mRNA sequence. So to get a correct/complete answer I would need that information.
Introns will need to be removed from the DNA sequence when you translate it to mRNA. Below is the example I used above with some randomly assigned introns as indicated by my underline.
DNA: 3’ATTGCGAGTCATTAC...
mRNA: 3'CGCUCAAUG...
Polypeptide: ArgSerMet...
As you can see I did not include the underlined letters from the DNA in my mRNA sequence and carried that through to the polypeptide.
