Transcription - DNA, RNA & the Codon Table Step by Step

Messenger RNA copies the coding strand, swapping U for every T.

highlighted = computed this step

RNA swaps T for U

Messenger RNA (mRNA) uses the same bases as DNA except that uracil (U) takes the place of thymine (T); A, C, and G are unchanged.

\text{T} \rightarrow \text{U}

The mRNA copies the coding strand

For our worked sequence the mRNA is the coding strand read straight across with U for T, giving AUGGCAUGCAAAUAA. Honesty note: this is the canonical path only — real transcription involves a promoter, a polymerase reading the template strand, and (in eukaryotes) splicing, none of which change the base-for-base correspondence shown here.

\text{coding strand} \xrightarrow{\;\text{T}\to\text{U}\;} \text{mRNA}