A DNA strand reads TACGGCATT. Give the mRNA sequence and the resulting amino acids.

Step 1 — Apply the base-pairing rules

Transcription copies the template strand into mRNA. DNA pairs with RNA like this:

Note that RNA carries uracil where DNA carries thymine.

Step 2 — Transcribe the strand

T A C G G C A T T A U G C C G U A A

Step 3 — Split the mRNA into codons

Reading begins at the start codon and continues in blocks of three:

AUG · CCG · UAA

Step 4 — Read the codon table

So the polypeptide is Met – Pro, and translation stops at the third codon.

Check

A stop codon does not add an amino acid, so a three-codon message produces a two-residue chain, not three. AUG at the front is the usual sign that the strand was given in the right reading frame.